Sample records for earth-trailing heliocentric orbit

  1. Lifetimes of Small Bodiesin Planetocentric (or Heliocentric) Orbits

    NASA Astrophysics Data System (ADS)

    Dobrovolskis, Anthony R.; Alvarellos, J. L.; Lissauer, J. J.

    2006-06-01

    Small bodies left over from the formation of the planets and satellites litter the Solar System, along with the debris from more recent collisions. These bodies are removed by expulsion from heliocentric or planetocentric orbit, as well as by collisions with planets, moons, and the Sun, with characteristic lifetimes depending on their orbits. However, the rate at which a given population of objects declines cannot be described by the simple exponential law used to describe radioactive decay. On the contrary, the removal of comets and remnant planetesimals has sometimes been described as "logarithmic decay''. Our work on the fate of ejecta from Hyperion (Dobrovolskis and Lissauer 2004, Icarus 169, 462--473), as well as recent results from other satellites, suggests instead that ejecta removal is best described by a "stretched exponential'' decay law, where the particle lifetimes increase as a fractional power of the elapsed time, suggestive of a diffusion process. Statistical analysis supports this conclusion, and enables us to determine the decay parameters. The results should be valuable in several contexts, including the delivery of meteorites to Earth and the bombardment history of the planets and their moons.

  2. Lifetimes of Small Bodies in Planetocentric (or Heliocentric) Orbits

    NASA Astrophysics Data System (ADS)

    Dobrovolskis, A. R.; Alvarellos, J. L.; Lissauer, J. J.

    2005-08-01

    Small bodies left over from the formation of the planets and satellites litter the Solar System, along with the debris from more recent collisions. These bodies are removed by expulsion from heliocentric or planetocentric orbit, as well as by collisions with planets, moons, and the Sun, with characteristic lifetimes depending on their orbits. However, the rate at which a given population of objects declines cannot be described by the simple exponential law used to describe radioactive decay. On the contrary, the removal of comets and remnant planetesimals has sometimes been described as ``logarithmic decay". Our work on the fate of ejecta from Hyperion (Dobrovolskis and Lissauer 2004, Icarus 169, 462-473) as well as our recent results from other satellites suggests instead that ejecta removal is best described by a ``stretched exponential" decay law, where the particle lifetimes increase as a fractional power of the elapsed time, suggestive of a diffusion process. Statistical analysis suports this conclusion, and enables us to determine the decay parameters. The results should be valuable in several contexts, including the delivery of meteorites to Earth and the bombardment history of the planets and their moons. NASA's PGG grant RTOP 344-30-50-01 supported this research.

  3. Lessons Learned from Natural Space Debris in Heliocentric Orbit: An Analogue for Hazardous Debris in Earth Orbit

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Wei, Hanying; Connors, Martin; Lai, Hairong; Delzanno, Gian Luca

    Interplanetary Field Enhancements (IFEs) were discovered almost 30 years ago in the PVO magnetic-field records. Our current understanding is that IFEs result from interactions between solar wind and clouds of nanometer-scale charged dust released in interplanetary collisions. These charged dust clouds are then accelerated by the solar wind and moving away from the Sun at near solar wind speed and detected by spacecraft in heliocentric orbit. The dynamics of the debris in heliocentric orbit is analogous to that mankind has placed into Earth orbit. There are lessons here that are worth exploring. The IFE formation hypothesis was supported by the discovery of co-orbiting materials associated with asteroid 2201 Oljato: IFE rate peaked when Oljato was close and IFE occurrence clustered in the longitudes near which the orbit of Oljato intersects the orbital plane of Venus. A followed up study with Venus Express observations suggested that the co-orbiting materials dissipated in 30 years. An important aspect of this evolution is that at collisional speeds of 20 km/s, a small body can destroy one 106 times more massive. This destruction of large debris by small debris could also be important in the evolution of the terrestrial debris. At 1AU, based on ACE and Wind observations, IFEs have a significant cluster in the longitude range between 195° and 225°. Thus we use the same IFE technique to identify the ‘parent’ Near-Earth Objects of co-orbiting materials which should be responsible for those IFEs. There are more than 5000 JPL documented NEOs whose ecliptic plane crossings are near to or inside the Earth’s orbit and whose orbital periods are less than five years. By comparing their trajectories, we find that the asteroid 138175 is a good candidate for the ‘parent’ body. This asteroid orbits the Sun in a 5.24° inclined elliptical orbit with a period of 367.96 days. Its descending node is at about 206°, where the IFE occurrence rate peaks. We also find that there is a spread of the IFE rate around the descending node, indicating that the co-orbiting materials have significant dispersion about the asteroid’s orbit. In summary, orbiting debris in orbits intersecting at high speeds can destroy itself quite efficiently, but with a long timescale. In deep space, this process is a step on the path between the asteroidal source population and the creation of solar system dust. This may be true for Earth-orbiting debris as well.

  4. Coupled Attitude-Orbit Dynamics and Control for an Electric Sail in a Heliocentric Transfer Mission

    PubMed Central

    Huo, Mingying; Zhao, Jun; Xie, Shaobiao; Qi, Naiming

    2015-01-01

    The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail. PMID:25950179

  5. Coupled attitude-orbit dynamics and control for an electric sail in a heliocentric transfer mission.

    PubMed

    Huo, Mingying; Zhao, Jun; Xie, Shaobiao; Qi, Naiming

    2015-01-01

    The paper discusses the coupled attitude-orbit dynamics and control of an electric-sail-based spacecraft in a heliocentric transfer mission. The mathematical model characterizing the propulsive thrust is first described as a function of the orbital radius and the sail angle. Since the solar wind dynamic pressure acceleration is induced by the sail attitude, the orbital and attitude dynamics of electric sails are coupled, and are discussed together. Based on the coupled equations, the flight control is investigated, wherein the orbital control is studied in an optimal framework via a hybrid optimization method and the attitude controller is designed based on feedback linearization control. To verify the effectiveness of the proposed control strategy, a transfer problem from Earth to Mars is considered. The numerical results show that the proposed strategy can control the coupled system very well, and a small control torque can control both the attitude and orbit. The study in this paper will contribute to the theory study and application of electric sail. PMID:25950179

  6. Probes to the Inferior Planets - A New Dawn for NEO and IEO Detection Technology Demonstration from Heliocentric Orbits Interior to the Earth's?

    NASA Astrophysics Data System (ADS)

    Grundmann, J. T.; Mottola, S.; Drentschew, M.; Drobczyk, M.; Kahle, R.; Maiwald, V.; Quantius, D.; Zabel, P.; Van Zoest, T.

    2011-11-01

    With the launch of MESSENGER and VENUS EXPRESS, a new wave of exploration of the inner solar system has begun. Noting the growing number of probes to the inner solar system, it is proposed to connect the expertise of the respective spacecraft teams and the NEO and IEO survey community to best utilize the extended cruise phases and to provide additional data return in support of pure science as well as planetary defence. Several missions to Venus and Mercury are planned to follow in this decade. Increased interest in the inferior planets is accompanied by several missions designed to study the Sun and the interplanetary medium (IPM) from a position near or in Earth orbit, such as the STEREO probes and SDO. These augment established solar observation capabilities at the Sun-Earth L1 Lagrangian point such as the SOHO spacecraft. Thus, three distinct classes of spacecraft operate or observe interior to Earth's orbit. All these spacecraft carry powerful multispectral cameras optimized for their respective primary targets. MESSENGER is scheduled to end its six-year interplanetary cruise in March 2011 to enter Mercury orbit, but a similarly extended cruise with several gravity-assists awaits the European Mercury mission BEPICOLOMBO. Unfortunately, the automatic abort of the orbit insertion manoeuvre has also left AKATSUKI (a.k.a. Venus Climate Orbiter (VCO), Planet-C) stranded in heliocentric orbit. After an unintended fly-by, the probe will catch up with Venus in approximately six years. Meanwhile, it stays mostly interior to Venus in a planet-leading orbit. In addition to the study of comets and their interaction with the IPM, observations of small bodies akin to those carried out by outer solar system probes are occasionally attempted with the equipment available. The study of structures in the interplanetary dust (IPD) cloud has been a science objective during the cruise phase of the Japanese Venus probe AKATSUKI from Earth to Venus. IPD observations in the astronomical H-band (1.65 ?m) are supported by its IR2 camera down to 1.5 ?W/m2sr in single 2 minute exposures. In the same setting, point sources of 13 mag can be detected. Obviously, a number of large asteroids exceed this threshold. The EARTHGUARD-I study, completed in 2003 by the DLR Institute of Planetary Research and Kayser-Threde under ESA contract, proposed a dedicated steerable 020...35 cm telescope and CCD camera payload on a probe to the inner solar system, to detect Near-Earth and Inner-Earth Objects (NEOs, IEOs) in favourable opposition geometry. A ride- share on a Mercury orbiter and a dedicated low-thrust propulsion spacecraft to a heliocentric 0.5 AU orbit were studied. A similar-sized telescope is presently being developed for the ASTEROIDFINDER satellite of DLR. Therefore, the technical feasibility of a number of asteroid observation scenarios involving spacecraft and targets interior to Earth's orbit is assessed based on the latest available spacecraft information and asteroid population models. A rough estimate of the required effort in terms of ground-based spacecraft operations and on-board resources is given for selected representative scenarios.

  7. The Case for a Geocentric rather than Heliocentric Origin of the Late Stage Heavy Bombardment (LHB) of the Moon and Tidal Evolution of its Orbit

    NASA Astrophysics Data System (ADS)

    Davis, P. M.; Stacey, F. D.

    2009-12-01

    Melt breccia samples returned from the Apollo mission have dates that suggest that the impacts that formed major basins on the Moon occurred between 3.8 and 4.0 Ga i.e., about 0.6 G years after Lunar formation. Three models have been proposed to explain the LHB. Heliocentric models including (1) The period marked the end of large-scale impacts associated with planetary formation and (2) It corresponded to a spike in impacts associated with major reorientation of the solar system (the ‘Nice model’), when the orbits Jupiter and Saturn became resonant, causing the orbits of Uranus and Neptune to become unstable and grow, scattering cometary and asteroidal fragments into Earth-Moon crossing orbits, and a geocentric model (3) It was due to collision with the last of a series of moonlets formed during Earth accretion which were swept up by tidal regression of a large Moon that had been formed near the Earth by a giant impact. While there is no smoking gun for any of these scenarios we will discuss a possible scenario for (3). Numerical calculations show that tidal regression of a large inner Moon sequentially traps exterior smaller moonlets into 2:1 resonance. Resonant trapping rapidly increases the eccentricity of their orbits causing them to become Moon-crossing. If the orbital radii of the moonlets had a resonance or Bode's law-type distribution, for the last collision to take place at 0.6 Gy, the Moon would have been at ~40 RE when it took place. One of the implications is that the associated LHB impacts would have significantly less relative velocity than those derived from asteroidal or cometary distances associated with (1) or (2). This may explain the low content of vapor condensate in the Lunar breccias. The tidal evolution from ~40 RE at 0.6 Gy requires a lower tidal friction than at present, but this has been evident for many years from tidal rhythmite data.

  8. Heliocentric synchronous halo for a solar sail with absorption

    Microsoft Academic Search

    A. A. Molostov; A. A. Shvartsburg

    1992-01-01

    Heliocentric synchronous halos are a type of heliocentric orbit for solar sails. Previous studies of such orbits have considered the sail surface to be absolutely reflecting and have not examined the consequences of its finite absorption. In the present work, an analysis is carried out which shows that the effect of absorption on synchronous halos differs in different regions of

  9. Models of Angular Momentum Input to a Circumterrestrial Swarm from Encounters with Heliocentric Planetesimals

    NASA Technical Reports Server (NTRS)

    Davis, D. R.; Greenberg, R.; Hebert, F.

    1985-01-01

    Models of lunar origin in which the Moon accretes in orbit about the Earth from material approaching the Earth from heliocentric orbits must overcome a fundamental problem: the approach orbits of such material would be, in the simplest approximation, equally likely to be prograde or retrograde about the Earth, with the result that accretion of such material adds mass but not angular momentum to circumterrestrial satellites. Satellite orbits would then decay due to the resulting drag, ultimately impacting onto the Earth. One possibility for adding both material and angular momentum to Earth orbit is investigated: imbalance in the delivered angular momentum between pro and retrograde Earth passing orbits which arises from the three body dynamics of planetesimals approaching the Earth from heliocentric space. In order to study angular momentum delivery to circumterrestrial satellites, the near Earth velocities were numerically computed as a function of distance from the Earth for a large array of orbits systematically spanning heliocentric phase space.

  10. Models of angular momentum input to a circumterrestrial swarm from encounters with heliocentric planetesimals

    NASA Technical Reports Server (NTRS)

    Herbert, F.; Davis, D. R.

    1984-01-01

    Preliminary experiments show that heliocentric planetesimals passing through the Earth environment possess significant angular momentum. However it also appears that these same planetesimals impacting a circularized circumterrestrial planetesimal swarm would likely remove angular momentum (though possibly increasing mean kinetic energy), presumably promoting both swarm infall upon the Earth and escape to heliocentric space. Only a distribution of highly eccentric satellite orbits with mean tangential velocities of a few tens of percent of local circular velocity would be immune against angular momentum loss to passing heliocentric planetesimals.

  11. Ancient Greek Heliocentric Views Hidden from Prevailing Beliefs?

    NASA Astrophysics Data System (ADS)

    Liritzis, Ioannis; Coucouzeli, Alexandra

    2008-03-01

    We put forward the working hypothesis that the heliocentric, rather than the geocentric view, of the Solar System was the essential belief of the early Greek philosophers and astronomers. Although most of them referred to the geocentric view, it is plausible that the prevalent religious beliefs about the sacred character of the Earth as well as the fear of prosecution for impiety (asebeia) prevented them from expressing the heliocentric view, even though they were fully aware of it. Moreover, putting the geocentric view forward, instead, would have facilitated the reception of the surrounding world and the understanding of everyday celestial phenomena, much like the modern presentation of the celestial sphere and the zodiac, where the Earth is at the centre and the Sun makes an apparent orbit on the ecliptic. Such an ingenious stance would have set these early astronomers in harmony with the dominant religious beliefs and, at the same time, would have helped them to 'save the appearances', without sacrificing the essence of their ideas. In Hellenistic and Roman times, the prevailing view was still the geocentric one. The brilliant heliocentric theory advanced by Aristarchos in the early third century B.C. was never established, because it met with hostility in Athens - Aristarchos was accused of impiety and faced the death penalty. The textual evidence suggests that the tight connection which existed between religion and the city-state (polis) in ancient Greece, and which led to a series of impiety trials against philosophers in Athens during the fifth and fourth centuries B.C., would have made any contrary opinion expressed by the astronomers seem almost a high treason against the state.

  12. SIRTF in Space: On-orbit Performance of the SIRTF Observatory

    NASA Astrophysics Data System (ADS)

    Werner, M.; Low, F.; Roellig, T.; Rieke, G.; Rieke, M.; Young, E.; Hoffmann, W. F.; Houck, J. R.; Fazio, G. G.; Hora, J. L.; Gehrz, R.; Soifer, T.; Helou, G.; Eisenhardt, P.; Gallagher, D.; Gautier, T. N.; Irace, W.; Lawrence, C.; Mainzer, A.; Simmons, L.; Jura, M.; Wright, E. L.; Cruikshank, D.; Keene, J.; Brandl, B. R.; Van Cleve, J. E.

    2003-12-01

    The Space Infrared Telescope Facility [SIRTF], NASA's Great Observatory for infrared exploration, was launched from Cape Canaveral on a Delta II rocket on August 25, 2003. As of mid-October, 2003, SIRTF was at a distance of about 0.03 au behind the Earth in its unique Earth-trailing heliocentric orbit. All spacecraft systems are operating extremely well in support of the on-going instrument checkout activities described in companion posters. In particular, the telescope has been cooled to its final operating temperature of 5.5K, and final focus has been achieved. All three instruments have returned engineering data, focus images, and initial observational results. In addition, both the uplink planning and command system, and the downlink data capture and pipeline processing system, are operating with high efficiency. This poster will provide an up-to-date overview of the overall status and performance of SIRTF. The research described here was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  13. Activity of Comets at Large Heliocentric Distances Pre-Perihelion

    NASA Astrophysics Data System (ADS)

    Meech, Karen Jean; Pittichova, J.; Bar-Nun, A.; Notesco, G.; Laufer, D.; Hainaut, O. R.; Lowry, S. C.; Yeomans, D. K.; Pitts, M.

    2008-09-01

    We present observational data for five long-period and dynamically new comets (C/1999 J2 (Skiff), C/2003 A2 (Gleason), C/2001 G1 (LONEOS),C/2003 O1 (LINEAR) and C/2001 Q1 (Neat) observed at heliocentric distances between 5.8 to 14.0 AU). All of the comets exhibited activity beyond the distance at which water ice sublimation can be significant on the inbound portions of their orbits. In particular, the dynamically new comet C/2003 A2 was observed active at 11.5 AU, pre-perihelion. We have conducted experiments on gas-laden amorphous ice samples and show that considerable gas omission occurs when the ice is heated below the temperature of the amorphous-crystalline ice phase transition (T 135K). We propose that annealing of amorphous water ice is the driver of activity in comets as they first enter the inner Solar System. Experimental data show that large grains can be ejected at low velocity during annealing and that the rate of brightening of the comet should decrease as the heliocentric distance decreases. These results are consistent with both historical observations of distant comet activity and with the data presented here. The ice annealing process can only release gases at temperatures above the temperature at which the amorphous ices condensed. Thus, if observations of the onset of activity in a dynamically new comet are ever made, the distance at which this occurs would be a sensitive indicator of the temperature at which the comet had formed. New surveys such as Pan STARRS, may be able to detect these comets while they are still inactive. This material is based upon work supported by the National Aeronautics and Space Administration through the NASA Astrobiology Institute under Cooperative Agreement No. NNA04CC08A issued through the Office of Space Science, by NASA Grant No. NNX07A044G.

  14. Analytical control laws of the heliocentric motion of the solar sail spacecraft

    NASA Astrophysics Data System (ADS)

    Gorbunova, Irina; Starinova, Olga

    2014-12-01

    The heliocentric motion of the solar sail spacecraft is described in classical Keplerian elements. The flat of solar sail with an ideal reflection coefficient is considered. The spacecraft performs a noncoplanar motion with the sun gravity and the light pressure. Disturbances of other celestial bodies gravity are not considered. We have received analytical terms for laws to control a solar sail, which ensure constancy or maximum rate of change of the Keplerian elements. To confirm the results correctness, we simulated the solar sail spacecraft. The spacecraft's initial orbit coincides with the average Earth orbit relative to the Sun. Authors developed a program complex to simulated the planar heliocentric movement and obtained results for motion simulation of flights to Mars and Venus. The results were compared with the simulation results obtained using the Pontryagin maximum principle.

  15. Statistical analysis of micrometeoroids at the heliocentric distance of Mercury

    NASA Astrophysics Data System (ADS)

    Borin, P.; Cremonese, G.; Marzari, F.

    2007-08-01

    This work shows preliminary results of a study of the orbital evolution of dust particles originating from the Main Belt in order to obtain a statistical analysis, then to provide an estimate of the flux of particles hitting the Mercury's surface. We can distinguish two population of meteoroids depending on their dynamical evolution: small particles (r < 1 cm) dominated by the Poynting-Robertson drag, and large particles (r > 1 cm) driven by gravity only. In this work we consider small particles and, in particular, the micrometeoroids produced by collisional fragmentation of cometary or asteroidal bodies. The main effects that determine the distribution of dust in the Solar System are the gravitational attractions of the Sun and planets, Poynting-Robertson drag, solar radiation pressure, solar wind pressure and the effects of different magnetic fields. In order to determine the meteoritic flux at the heliocentric distance of Mercury we utilize the dynamical evolution model of dust particles of Marzari and Vanzani (1994) that numerically solves a (N+1)+M body problem (Sun + N planets + M body with zero mass) with the high-precision integrator RA15 (Everhart 1985). The solar radiation pressure and Poynting-Robertson drag, together with the gravitational interactions of the planets, are taken as major perturbing forces affecting the orbital evolution of the dust particles. We will perform numerical simulations with different initial conditions for the dust particles, depending on the sources, with the aim of estimating to flux of dust on the surface of Mercury. Meteoroid impacts have a very important role in the evolution of Mercury's surface and exosphere. Since the exobase is presently on the surface of the planet, the sources and sinks of the exosphere are tightly linked to the composition and structure of the planet surface. We intend also to evaluate a possible asymmetry between the leading and trailing surface of Mercury in terms of impact frequency.

  16. Proof-of-Concept Trajectory Designs for a Multi-Spacecraft, Low-Thrust Heliocentric Solar Weather Buoy Mission

    NASA Technical Reports Server (NTRS)

    Muller, Ronald; Franz, Heather; Roberts, Craig; Folta, Dave

    2005-01-01

    A new solar weather mission has been proposed, involving a dozen or more small spacecraft spaced at regular, constant intervals in a mutual heliocentric circular orbit between the orbits of Earth and Venus. These solar weather buoys (SWBs) would carry instrumentation to detect and measure the material in solar flares, solar energetic particle events, and coronal mass ejections as they flowed past the buoys, serving both as science probes and as a radiation early warning system for the Earth and interplanetary travelers to Mars. The baseline concept involves placing a mothercraft carrying the SWBs into a staging orbit at the Sun-Earth L1 libration point. The mothercraft departs the L1 orbit at the proper time to execute a trailing-edge lunar flyby near New Moon, injecting it into a heliocentric orbit with its perihelion interior to Earth s orbit. An alternative approach would involve the use of a Double Lunar Swingby (DLS) orbit, rather than the L1 orbit, for staging prior to this flyby. After injection into heliocentric orbit, the mothercraft releases the SWBs-all equipped with low-thrust pulsed plasma thrusters (PPTs)-whereupon each SWB executes a multi-day low-thrust finite bum around perihelion, lowering aphelion such that each achieves an elliptical phasing orbit of different orbital period from its companions. The resulting differences in angular rates of motion cause the spacecraft to separate. While the lead SWB achieves the mission orbit following an insertion burn at its second perihelion passage, the remaining SWBs must complete several revolutions in their respective phasing orbits to establish them in the mission orbit with the desired longitudinal spacing. The complete configuration for a 14 SWB scenario using a single mothercraft is achieved in about 8 years, and the spacing remains stable for at least a further 6 years. Flight operations can be simplified, and mission risk reduced, by employing two mothercraft instead of one. In this scenario: the second mothercraft stays in a libration-point or DLS staging orbit until the first mothercraft has achieved nearly 180 separation from the Earth. The timing of the second mothercraft's subsequent lunar flyby is planned such that this spacecraft will be located 180 from the first mothercraft upon completion of its heliocentric circularization maneuvers. Both groups of satellites then only have to spread out over 180 to obtain full 360 coverage around the Sun.

  17. 3D high-speed escape heliocentric trajectories by all-metallic-sail low-mass sailcraft

    Microsoft Academic Search

    Giovanni Vulpetti

    1996-01-01

    Considering a photon solar-sail spacecraft with a lightness number in the range [12–1) (all-metallic sail), this paper analyses a class of heliocentric trajectories, characterized by orbital angular-momentum reversal, delivering a considerable cruise speed (10–20 AU\\/yr) and allowing a sailcraft to access any celestial latitude [??2, +?2], depending primarily on the perihelion distance. It is found out that, if the lightness

  18. CCD-photometry of comets at large heliocentric distances

    NASA Technical Reports Server (NTRS)

    Mueller, Beatrice E. A.

    1992-01-01

    CCD imaging and time series photometry are used to determine the state of activity, nuclear properties and eventually the rotational motion of cometary nuclei. Cometary activity at large heliocentric distances and mantle evolution are not yet fully understood. Results of observations carried out at the 2.1 telescope on Kitt Peak April 10-12 and May 15-16, 1991 are discussed. Color values and color-color diagrams are presented for several comets and asteroids. Estimations of nuclear radii and shapes are given.

  19. Heliocentric distance dependence of the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.

    1977-01-01

    Recent and ongoing planetary missions have provided extensive observations of the variations of the Interplanetary Magnetic Field (IMF) both in time and with heliocentric distance from the sun. Large time variations in both the IMF and its fluctuations were observed. These are produced predominantly by dynamical processes in the interplanetary medium associated with stream interactions. Magnetic field variations near the sun are propagated to greater heliocentric distances, also contributing to the observed variablity of the IMF. Temporal variations on a time-scale comparable to or less than the corotation period complicate attempts to deduce radial gradients of the field and its fluctuations from the various observations. However, recent measurements inward to 0.46 AU and outward to 5 AU suggest that the radial component of the field on average decreases approximately as r to the minus second power, while the azimuthal component decreases more rapidly than the r to the minum first power dependence predicted by simple theory. This, and other observations, are discussed.

  20. 67P/Churyumov-Gerasimenko: start of activity and heliocentric light curve

    NASA Astrophysics Data System (ADS)

    Tubiana, C.; Snodgrass, C.; Bramich, D.; Boehnhardt, H.; Barrera, L.

    2012-09-01

    Comets are believed to be widely unmodified remnants from the formation of the solar system; their study can give important insights into the conditions prevailing at the time of the planetary system formation. After the success of the Giotto mission to comet 1P/Halley, the European Space Agency (ESA) approved in the early nineties a new space mission with a comet as main target: Rosetta, which will rendezvous with come 67P/Churyumov-Gerasimenko (67P/C-G) in 2014. 67P/C-G is a Jupiter family comet with orbital period of 6.56 years. Due to repeated encounters with Jupiter, the orbital evolution of 67P/C-G is chaotic. The last encounter in February 1959 occurred at a distance of only 0.0518 AU and produced drastic changes in perihelion distance, eccentricity, inclination, orbital period and possibly led to its discovery in 1969. After 67P/C-G was selected as target comet of Rosetta mission, observational campaigns and theoretical investigations were performed in order to establish a detailed portrait of 67P/C-G in preparation of the rendezvous with the spacecraft ([1], [2], [3], [4]). Here we present ground-based observations of 67P/CG obtained between July 2007 and March 2008 at ESO VLT using the FORS2 instrument. The comet was moving inbound, from 4.6 AU to 3.4 AU. The orbital arc covered by our observation is the same where 67P/C-G will be in 2014 when the rendezvous with the Rosetta spacecraft will take place, thus of highly interest for mission planning. Since the comet's activity around perihelion has shown similar behaviour during the last three orbital passages, it is fair to assume that the comet's behavior at large heliocentric distance has not changed from one orbital revolution to the other, leading us to expect that during its approach to 67P/CG, Rosetta will find the same conditions detected during our observations. A considerable difficulty in observing 67P/C-G during the past years has been its position against crowded fields towards the galactic centre for much of this time (Fig. 1 - top). The 2007/8 data presented here was particularly difficult, and the comet will once again be badly placed for Earth based observations in 2014/5. We made use of the technique of Difference Image Analysis (as implemented in the DanDIA software, [5]), which is commonly used in variable star and exoplanet research, to remove background sources and extract images of the comet (Fig. 1 - bottom). We determined that the comet became active during the period November 2007 - March 2008, at a distance of 4.1-3.4 AU from the Sun. The comet will reach this distance, and probably become active again, in April- September 2014. To investigate the longer period activity cycle of the comet we compiled the heliocentric light curve of the comet, making use of images of 67P/C-G taken during the last three apparitions taken from the ESO archive. A preliminary light curve is shown in 2. This information will be used for planning observing campaigns, both from the ground and using OSIRIS on board Rosetta.

  1. Heliocentric halos for a solar sail with absorption

    Microsoft Academic Search

    A. A. Molostov; A. A. Shvartsburg

    1992-01-01

    The effect of the finite absorption of the solar sail on the halo orbits is investigated analytically. An analysis of optimal halo orbits indicates that the effect of absorption does not lead to qualitative changes but rather results in a continuously increasing distortion of the ideal case in proportion to this factor. Corrections for absorption are required for the adequate

  2. New estimate of the micrometeoroids flux at the heliocentric distance of Mercury

    NASA Astrophysics Data System (ADS)

    Borin, Patrizia; Cremonese, Gabriele; Marzari, Francesco

    This work shows preliminary results of a study of the orbital evolution of dust particles originating from the Main Belt in order to obtain a statistical analysis, then to provide an estimate of the flux of particles hitting the Mercury's surface. Meteoritic flux on Mercury really depends on the particle size, because meteoroids of different size follow different dynamical evolution. In this work we consider meteoritic sizes smaller than 1 cm that are particles with a dynamical evolution dominated by the Poynting-Robertson effect. The meteoroid impact mechanism seems to be an important source of neutral atoms contributing to the exosphere and, according to recent papers, mostly due to particles smaller than 1 cm. Unfortunately the dynamical studies and statistics of meteoroids smaller than 1 cm are based on quite old papers and always extrapolated from calculations made for the Earth. This is the reason why we are working on a dynamical model following small dust particles that may hit the surface of Mercury. Up to now we have taken into account only particles coming from the Main Belt. The main effects that determine the distribution of dust in the Solar System are the gravitational attractions of the Sun and planets, Poynting-Robertson drag, solar radiation pressure, solar wind pressure and the effects of different magnetic fields. In order to determine the meteoritic flux at the heliocentric distance of Mercury we utilize the dynamical evolution model of dust particles of Marzari and Vanzani (1994) that numerically solves a (N+1)+M body problem (Sun + N planets + M body with zero mass) with the high-precision integrator RA15 (Everhart 1985). The solar radiation pressure and Poynting-Robertson drag, together with the gravitational interactions of the planets, are taken as major perturbing forces affecting the orbital evolution of the dust particles. We have performed numerical simulations with different initial conditions for the dust particles, depending on the sources, with the aim of estimating to flux of dust on the surface of Mercury. In this work we will report the first interesting estimate of the flux of small particles, and their velocity distribution, hitting the surface of Mercury. We intend also to evaluate a possible asymmetry between the leading and trailing surface of Mercury in terms of impact frequency.

  3. Heliocentric distance and temporal dependence of the interplanetary density-magnetic field magnitude correlation

    NASA Technical Reports Server (NTRS)

    Roberts, D. A.

    1990-01-01

    The Helios, IMP 8, ISEE 3, ad Voyager 2 spacecraft are used to examine the solar cycle and heliocentric distance dependence of the correlation between density n and magnetic field magnitude B in the solar wind. Previous work had suggested that this correlation becomes progressively more negative with heliocentric distance out to 9.5 AU. Here it is shown that this evolution is not a solar cycle effect, and that the correlations become even more strongly negative at heliocentric distance larger than 9.5 AU. There is considerable variability in the distributions of the correlations at a given heliocentric distance, but this is not simply related to the solar cycle. Examination of the evolution of correlations between density and speed suggest that most of the structures responsible for evolution in the anticorrelation between n and B are not slow-mode waves, but rather pressure balance structures. The latter consist of both coherent structures such as tangential discontinuities and the more generally pervasive 'pseudosound' which may include the coherent structures as a subset.

  4. Pioneer 10 observations of zodiacal light brightness near the ecliptic: Changes with heliocentric distance

    Microsoft Academic Search

    M. So HANNER; J. Go SPARROW; J. L. WEINBERG; D. Eo BEESON

    Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees.The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background

  5. Interest of old data for the determination of the heliocentric distance of Pluto

    E-print Network

    53 Interest of old data for the determination of the heliocentric distance of Pluto L. Beauvalet1, 75014 Paris, France Abstract Pluto was discovered in 1930. It is also the multiple system which has been known for the longest time with the discovery of its first satellite Charon in 1978. Because of Pluto

  6. The trend of production rates with heliocentric distance for comet P/Halley

    NASA Astrophysics Data System (ADS)

    Fink, U.

    1994-03-01

    Comet P/Halley was observed spectroscopically in the wavelength range 5200-10,400 A during 10 observing runs, roughly a month apart from 1985 August 28 to 1986 June 6. The observations span a heliocentric distance from 0.73 to 2.52 AU. This data set is analyzed to determine the course of the production rate with heliocentric distance for C2, NH2, CN, and the continuum. The effect of changing the Haser scale lengths and their heliocentric distance dependence is examined. The production rate ratios to water change only in a minor way, but the absolute values of the production rates are more severely affected. Fluorescent efficiencies, or g-factors for the CN red system are calculated, and band intensity ratios for NH2 and CN are presented. Using presently available fluorescence efficiencies and Haser scale lengths, mixing ratios for the parents of C2, CN, and NH2 with respect to water are: 0.34 +/- 0.07%, 0.15 +/- 0.04%, and 0.13 +/- 0.05%. It is found that these mixing ratios are essentially constant over the heliocentric distance range of the observations, implying a rather uniform nucleus and uniform outgassing characteristics, although there are indications of smaller scale day-to-day variations. The results provide strong observational confirmation that water evaporation controls the activity of the comet over the distance range studied. Continuum values Af rho are determined, and their ratios to QH2O are found to have a clear dependence with heliocentric distance approximately r-1.0 with a post-perihelion enhancement. No correlation of the production rate ratios with light curve of P/Halley were found, nor was there any correlation of the C2 or CN production with the dust.

  7. The amplitudes of interplanetary fluctuations - Stream structure, heliocentric distance, and frequency dependence

    NASA Technical Reports Server (NTRS)

    Roberts, D. A.; Goldstein, M. L.; Klein, L. W.

    1990-01-01

    A study is presented of the heliocentric distance, frequency, and stream structure dependence of the amplitudes of interplanetary fluctuations in the velocity and magnetic field from 0.3 to nearly 20 AU and for spacecraft-frame periods of 10 days to a few hours. Evidence is presented that, at a given heliocentric distance, the amplitude of the magnetic field fluctuations is proportional to the magnitude of the field, nearly independently of the solar wind speed. The radial evolution of magnetic fluctuations is shown to be nearly consistent with WKB expectations except at smaller scales in the inner heliosphere and at the largest scales in the outer heliosphere. While the large-scale velocity fluctuations are kinetic energy-dominated in the inner heliosphere due to the presence of streams, the magnetic fluctuation energy eventually comes to be slightly dominant over the kinetic energy at all scales. The theoretical implications of the results are considered.

  8. Effect of a drag force due to absorption of solar radiation on solar sail orbital dynamics

    NASA Astrophysics Data System (ADS)

    Kezerashvili, Roman Ya.; Vázquez-Poritz, Justin F.

    2013-03-01

    While solar electromagnetic radiation can be used to propel a solar sail, it is shown that the Poynting-Robertson effect related to the absorbed portion of the radiation leads to a drag force in the transversal direction. The Poynting-Robertson effect is considered for escape trajectories, Heliocentric bound orbits and non-Keplerian bound orbits. For escape trajectories, this drag force diminishes the cruising velocity, which has a cumulative effect on the Heliocentric distance. For Heliocentric and non-Keplerian bound orbits, the Poynting-Robertson effect decreases its orbital speed, thereby causing it to slowly spiral towards the Sun. Since the Poynting-Robertson effect is due to the absorbed portion of the electromagnetic radiation, degradation of a solar sail implies that this effect becomes enhanced during a mission.

  9. Spitzer Orbit Determination During In-orbit Checkout Phase

    NASA Technical Reports Server (NTRS)

    Menon, Premkumar R.

    2004-01-01

    The Spitzer Space Telescope was injected into heliocentric orbit on August 25, 2003 to observe and study astrophysical phenomena in the infrared range of frequencies. The initial 60 days was dedicated to Spitzer's "In-Orbit Checkout (IOC)" efforts. During this time high levels of Helium venting were used to cool down the telescope. Attitude control was done using reaction wheels, which in turn were de-saturated using cold gas Nitrogen thrusting. Dense tracking data (nearly continuous) by the Deep Space network (DSN) were used to perform orbit determination and to assess any possible venting imbalance. Only Doppler data were available for navigation. This paper deals with navigation efforts during the IOC phase. It includes Dust Cover Ejection (DCE) monitoring, orbit determination strategy validation and results and assessment of non-gravitational accelerations acting on Spitzer including that due to possible imbalance in Helium venting.

  10. The heliocentric evolution of cometary infrared spectra - Results from an organic grain model

    NASA Astrophysics Data System (ADS)

    Chyba, C. F.; Sagan, C.; Mumma, M. J.

    1989-06-01

    An emission feature peaking near 3.4 microns that is typical of C-H stretching in hydrocarbons and which fits a simple, two-component thermal emission model for dust in the cometary coma, has been noted in observations of Comets Halley and Wilson. A noteworthy consequence of this modeling is that, at about 1 AU, emission features at wavelengths longer than 3.4 microns come to be 'diluted' by continuum emission. A quantitative development of the model shows it to agree with observational data for Comet Halley for certain, plausible values of the optical constants; the observed heliocentric evolution of the 3.4-micron feature thereby furnishes information on the composition of the comet's organic grains.

  11. LISA Orbits

    NASA Astrophysics Data System (ADS)

    Povoleri, Angelo; Kemble, Stephen

    2006-11-01

    The LISA formation is composed of 3 spacecraft in an equilateral triangle formation. The baseline formation has a 5million km radius and lies in a heliocentric orbit 20deg away from the Earth. Earth's gravity induces a perturbation on the nominal Keplerian motion of the formation, generating a change in the relative ranges and thus a Doppler that can be very harmful for the scientific goals of the mission. Zero station keeping options are preferred, so alternative passive solutions have to be found. This paper presents results obtained by optimising the formation design, particularly the orientation of the eccentricity vectors. Formation design optimisation proves to be an effective strategy, succeeding in keeping the relative range rate between any two spacecraft below 13m/s. Another possible source of perturbation arises from the self-acceleration induced on the formation by the imperfect mass distribution on each spacecraft. The effect of this perturbing acceleration on the motion of the formation has been studied, and the formation design has been re-optimised assuming several levels of perturbation. This approach has shown the result that such effect can be even beneficial on the formation stability, provided that the acceleration doesn't exceed 1e-8m/s2. The transfer to the optimal stability formation has then been optimised, assuming a launch window throughout the year. Mission ?v to a specific target is quite sensitive to the launch date: trailing formations are most effectively reached if the launch occurs at Earth's apohelion (summer), while the opposite applies to leading formations. A strategy where leading and trailing formations are alternatively targeted according to the launch date has proved to be the most effective in keeping the ?v as low as possible.

  12. Telemetry coding study for the international magnetosphere explorers, mother/daughter and heliocentric missions. Volume 2: Final report

    NASA Technical Reports Server (NTRS)

    Cartier, D. E.

    1973-01-01

    A convolutional coding theory is given for the IME and the Heliocentric spacecraft. The amount of coding gain needed by the mission is determined. Recommendations are given for an encoder/decoder system to provide the gain along with an evaluation of the impact of the system on the space network in terms of costs and complexity.

  13. A Synoptic Analysis of the Change from the Geocentric to the Heliocentric Conception of the Solar System.

    ERIC Educational Resources Information Center

    Wilson, Roosevelt L.

    The changes which occurred in man's view of the solar system from the time of Ptolemy to that of Galileo are presented. Contained is a brief review of the chain of events which resulted in the acceptance of a heliocentric system. Ptolomy's theory is described and a diagram illustrates the paths of the epicycle of Mars according to his geocentric…

  14. Possible Periodic Orbit Control Maneuvers for an eLISA Mission

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Welter, Gary L.

    2012-01-01

    This paper investigates the possible application of periodic orbit control maneuvers for so-called evolved-LISA (eLISA) missions, i.e., missions for which the constellation arm lengths and mean distance from the Earth are substantially reduced. We find that for missions with arm lengths of 106 km and Earth-trailing distance ranging from approx. 12deg to 20deg over the science lifetime, the occasional use of the spacecraft micro-Newton thrusters for constellation configuration maintenance should be able to essentially eliminate constellation distortion caused by Earth-induced tidal forces at a cost to science time of only a few percent. With interior angle variation kept to approx. +/-0:1deg, the required changes in the angles between the laser beam pointing directions for the two arms from any spacecraft could be kept quite small. This would considerably simplify the apparatus necessary for changing the transmitted beam directions.

  15. Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances

    E-print Network

    Raghuram, Susarla

    2014-01-01

    In comets the atomic oxygen green to red-doublet emission intensity ratio (G/R ratio) of 0.1 has been used to confirm H$_2$O as the parent species producing oxygen emission lines. The larger ($>$0.1) value of G/R ratio observed in a few comets is ascribed to the presence of higher CO$_2$ and CO relative abundances in the cometary coma. We aim to study the effect of CO$_2$ and CO relative abundances on the observed G/R ratio in comets observed at large ($>$2 au) heliocentric distances by accounting for important production and loss processes of O($^1$S) and O($^1$D) in the cometary coma. Recently we have developed a coupled chemistry-emission model to study photochemistry of O($^1$S) and O($^1$D) atoms and the production of green and red-doublet emissions in comets Hyakutake and Hale-Bopp. In the present work we applied the model to six comets where green and red-doublet emissions are observed when they are beyond 2 au from the Sun. In a water-dominated cometary coma and with significant ($>$10%) CO$_2$ relati...

  16. Orbit Determination and Navigation of the Solar Terrestrial Relations Observatory (STEREO)

    NASA Technical Reports Server (NTRS)

    Mesarch, Michael A.; Robertson, Mika; Ottenstein, Neil; Nicholson, Ann; Nicholson, Mark; Ward, Douglas T.; Cosgrove, Jennifer; German, Darla; Hendry, Stephen; Shaw, James

    2007-01-01

    This paper provides an overview of the required upgrades necessary for navigation of NASA's twin heliocentric science missions, Solar TErestrial RElations Observatory (STEREO) Ahead and Behind. The orbit determination of the STEREO spacecraft was provided by the NASA Goddard Space Flight Center's (GSFC) Flight Dynamics Facility (FDF) in support of the mission operations activities performed by the Johns Hopkins University Applied Physics Laboratory (APL). The changes to FDF's orbit determination software included modeling upgrades as well as modifications required to process the Deep Space Network X-band tracking data used for STEREO. Orbit results as well as comparisons to independently computed solutions are also included. The successful orbit determination support aided in maneuvering the STEREO spacecraft, launched on October 26, 2006 (00:52 Z), to target the lunar gravity assists required to place the spacecraft into their final heliocentric drift-away orbits where they are providing stereo imaging of the Sun.

  17. Gravity and Orbits: Orbits

    NSDL National Science Digital Library

    National Science Teachers Association (NSTA)

    2006-11-01

    This Science Object is the third of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of how gravitational forces influence the motion of an object in orbit. When a force acts toward a single center, an object's forward motion and its motion toward that center can combine to create a curved path around the center. Gravity governs the motion of all objects in the solar system. The Sun's gravitational pull holds the Earth and other planets in their orbits, just as the planets' gravitational pull keeps their moons in orbit around them. Learning Outcomes:? Describe the conditions that would lead an object into orbital motion in terms of the effects of gravitational force.? Explain how an object orbits a planet in terms of trajectories and free fall.? Identify gravity as the force that keeps the planets in their orbits around the Sun and the moons in their orbits around the planets.

  18. Kepler Stars with Multiple Transiting Planet Candidates

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.

    2012-01-01

    NASA's Kepler spacecraft was launched into an Earth-trailing heliocentric orbit in March of 2009. Kepler is designed to conduct a statistical census of planetary system properties using transit photometry. Among the most exciting early results from Kepler are target stars found to have photometric signatures that suggest the presence of more than one transiting planet. Individual transiting planets provide information on the size and orbital period distributions of exoplanets. Multiple transiting planets provide additional information on the spacing and flatness distributions of planetary systems. Results to d ate and plans for future analysis will be presented.

  19. Orbital acrobatics in the Sun-Earth-Moon system

    NASA Technical Reports Server (NTRS)

    Farquhar, Robert W.; Dunham, D. W.; Hsu, S. C.

    1986-01-01

    Unconventional trajectory techniques for space missions in the Sun-Earth-Moon system, including libration-point orbits, gravity-assist maneuvers, and Earth-return trajectories are reviewed. The ISEE-3/ICE flight experience is used to illustrate the utility of libration-point orbits called halo-orbits. Five lunar gravity-assist maneuvers used by the ISEE-3/ICE spacecraft are discussed. The final lunar swingby sent the spacecraft into a heliocentric trajectory that will eventually intercept Comet Giacobini-Zinner. As an example of the Earth-return trajectory concept, a proposed mission that includes flybys of three comets and two asteroids is described.

  20. Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances

    NASA Astrophysics Data System (ADS)

    Raghuram, Susarla; Bhardwaj, Anil

    2014-06-01

    Context. In comets, the atomic oxygen green (5577 Å) to red-doublet (6300, 6364 Å) emission intensity ratio (G/R ratio) of 0.1 has been used to confirm H2O as the parent species producing forbidden oxygen emission lines. The larger (>0.1) value of G/R ratio observed in a few comets is ascribed to the presence of higher CO2 and CO relative abundances in the cometary coma. Aims: We aim to study the effect of CO2 and CO relative abundances on the observed G/R ratio in comets observed at large (>2 au) heliocentric distances by accounting for important production and loss processes of O(1S) and O(1D) atoms in the cometary coma. Methods: Recently we have developed a coupled chemistry-emission model to study photochemistry of O(1S) and O(1D) atoms and the production of green and red-doublet emissions in comets Hyakutake and Hale-Bopp. In the present work we applied the model to six comets where green and red-doublet emissions are observed when they are beyond 2 au from the Sun. Results: The collisional quenching of O(1S) and O(1D) can alter the G/R ratio more significantly than that due to change in the relative abundances of CO2 and CO. In a water-dominated cometary coma and with significant (>10%) CO2 relative abundance, photodissociation of H2O mainly governs the red-doublet emission, whereas CO2 controls the green line emission. If a comet has equal composition of CO2 and H2O, then ~50% of red-doublet emission intensity is controlled by the photodissociation of CO2. The role of CO photodissociation is insignificant in producing both green and red-doublet emission lines and consequently in determining the G/R ratio. Involvement of multiple production sources in the O(1S) formation may be the reason for the observed higher green line width than that of red lines. The G/R ratio values and green and red-doublet line widths calculated by the model are consistent with the observation. Conclusions: Our model calculations suggest that in low gas production rate comets the G/R ratio greater than 0.1 can be used to constrain the upper limit of CO2 relative abundance provided the slit-projected area on the coma is larger than the collisional zone. If a comet has equal abundances of CO2 and H2O, then the red-doublet emission is significantly (~50%) controlled by CO2 photodissociation and thus the G/R ratio is not suitable for estimating CO2 relative abundance.

  1. Sailcraft at high speed by orbital angular momentum reversal

    Microsoft Academic Search

    Giovanni Vulpetti

    1997-01-01

    Considering a photon solar sail spacecraft with a lightness number (?) in the range [0.5-1) (all-metallic sails), this paper analyses a class of heliocentric trajectories, characterized by orbital angular-momentum reversal, delivering a considerable final spacecraft speed. It is found out that, if both the radial and transversal lightness numbers satisfy certain inequality constraints, the sailcraft in the solar gravitational field

  2. Extrasolar Planetary Imaging Coronagraph (EPIC)

    NASA Technical Reports Server (NTRS)

    Clampin, Mark

    2009-01-01

    EPIC is a NASA mission being studied to detect and characterize Jovian and superEarth planets, and, the dust/debris disks surrounding the parent star. It will be launched into a heliocentric Earth trailing orbit and operate for 5 years. EPIC would operate over the wavelength range of 480 - 960 nm with spectral resolutions of R < 50 and employs a visible nulling coronagraph (VNC) to suppress the starlight, yielding contrast ratios of greater than 9 orders of magnitude. We will discuss the science mission, and its role in the search for habitable planets.

  3. Program manual for HILTOP, a heliocentric interplanetary low thrust trajectory optimization program. Part 1: User's guide

    NASA Technical Reports Server (NTRS)

    Mann, F. I.; Horsewood, J. L.

    1974-01-01

    A performance-analysis computer program, that was developed explicitly to generate optimum electric propulsion trajectory data for missions of interest in the exploration of the solar system is presented. The program was primarily designed to evaluate the performance capabilities of electric propulsion systems, and in the simulation of a wide variety of interplanetary missions. A numerical integration of the two-body, three-dimensional equations of motion and the Euler-Lagrange equations was used in the program. Transversality conditions which permit the rapid generation of converged maximum-payload trajectory data, and the optimization of numerous other performance indices for which no transversality conditions exist are included. The ability to simulate constrained optimum solutions, including trajectories having specified propulsion time and constant thrust cone angle, is also in the program. The program was designed to handle multiple-target missions with various types of encounters, such as rendezvous, stopover, orbital capture, and flyby. Performance requirements for a variety of launch vehicles can be determined.

  4. Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the Lunar Atmosphere Dust Environment Explorer (LADEE) Spacecraft

    NASA Technical Reports Server (NTRS)

    Genova, Anthony L.; Loucks, Michael; Carrico, John

    2014-01-01

    The purpose of this extended abstract is to present results from a failed lunar-orbit insertion (LOI) maneuver contingency analysis for the Lunar Atmosphere Dust Environment Explorer (LADEE) mission, managed and operated by NASA Ames Research Center in Moffett Field, CA. The LADEE spacecrafts nominal trajectory implemented multiple sub-lunar phasing orbits centered at Earth before eventually reaching the Moon (Fig. 1) where a critical LOI maneuver was to be performed [1,2,3]. If this LOI was missed, the LADEE spacecraft would be on an Earth-escape trajectory, bound for heliocentric space. Although a partial mission recovery is possible from a heliocentric orbit (to be discussed in the full paper), it was found that an escape-prevention maneuver could be performed several days after a hypothetical LOI-miss, allowing a return to the desired science orbit around the Moon without leaving the Earths sphere-of-influence (SOI).

  5. Orbital Resonance and Solar Cycles

    E-print Network

    P. A. Semi

    2009-03-29

    We present an analysis of planetary moves, encoded in DE406 ephemerides. We show resonance cycles between most planets in Solar System, of differing quality. The most precise resonance - between Earth and Venus, which not only stabilizes orbits of both planets, locks planet Venus rotation in tidal locking, but also affects the Sun: This resonance group (E+V) also influences Sunspot cycles - the position of syzygy between Earth and Venus, when the barycenter of the resonance group most closely approaches the Sun and stops for some time, relative to Jupiter planet, well matches the Sunspot cycle of 11 years, not only for the last 400 years of measured Sunspot cycles, but also in 1000 years of historical record of "severe winters". We show, how cycles in angular momentum of Earth and Venus planets match with the Sunspot cycle and how the main cycle in angular momentum of the whole Solar system (854-year cycle of Jupiter/Saturn) matches with climatologic data, assumed to show connection with Solar output power and insolation. We show the possible connections between E+V events and Solar global p-Mode frequency changes. We futher show angular momentum tables and charts for individual planets, as encoded in DE405 and DE406 ephemerides. We show, that inner planets orbit on heliocentric trajectories whereas outer planets orbit on barycentric trajectories.

  6. The coupled orbital and thermal evolution of Triton

    NASA Technical Reports Server (NTRS)

    Ross, Martin N.; Schubert, Gerald

    1990-01-01

    The coupled orbital and thermal evolution of Triton is simulated with a model of the satellite having temperature-dependent k/Q (k is the second degree Love number and Q is the tidal dissipation factor). Large changes in orbital and interior properties occur in a short time span of less than 10 to the 8th years. The peak tidal heating rate exceeds the radioactive heating rate by a factor of at least 1000. The ability of tidal heating to overwhelm solid state convection and cause global melting is unequivocally demonstrated. Triton's initial thermal state and composition are shown to control the length of time that passes between capture from heliocentric orbit and the occurrene of swift and dramatic changes in orbital and internal properties. This time interval could have been several billion years.

  7. Constraining the Dust Coma Properties of Comet C/Siding Spring (2013 A1) at Large Heliocentric Distances

    E-print Network

    Li, Jian-Yang; Kelley, Michael S P; Farnham, Tony L; A'Hearn, Michael F; Mutchler, Max J; Lisse, Carey M; Delamere, W Alan

    2014-01-01

    The close encounter of Comet C/2013 A1 (Siding Spring) with Mars on October 19, 2014 presented an extremely rare opportunity to obtain the first flyby quality data of the nucleus and inner coma of a dynamically new comet. However, the comet's dust tail potentially posed an impact hazard to those spacecraft. To characterize the comet at large heliocentric distances, study its long-term evolution, and provide critical inputs to hazard modeling, we imaged C/Siding Spring with the Hubble Space Telescope when the comet was at 4.58, 3.77, and 3.28 AU from the Sun. The dust production rate, parameterized by the quantity Af$\\rho$, was 2500, 2100, and 1700 cm (5000-km radius aperture) for the three epochs, respectively. The color of the dust coma is 5.0$\\pm$0.3$\\%$/100 nm for the first two epochs, and 9.0$\\pm$0.3$\\%$/100 nm for the last epoch, and reddens with increasing cometocentric distance out to ~3000 km from the nucleus. The spatial distribution and the temporal evolution of the dust color are most consistent wi...

  8. Characteristics of large Forbush-type decreases in the cosmic radiation. II - Observations at different heliocentric radial distances

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Lockwood, J. A.; Jokipii, J. R.

    1986-01-01

    Cosmic ray data from IMP 8, Voyager 1 and 2, Pioneer 10 are used to investigate the heliocentric radial dependence of the characteristics of about 20 Forbush-type transient decreases which occurred from 1978 to 1984. These characteristics include the recovery time, the amplitude, and the time to decrease to minimum. It is found that the average recovery time is about 5 times longer at R = 30 AU than at 1 AU. The magnitudes of the transient decreases are observed to decrease about 1.5 percent/AU on average so that the magnitude of the decrease is half as great at R about 30 AU as at 1 AU. The time for the cosmic ray intensity to decrease to the minimum in the transient decrease is found to be greater at larger distances and is about 5 times longer at R = 30 AU than at 1 AU. The behavior of these effects as a function of radius is obviously related to the evolution of the disturbances causing the transient decreases as they propagate outward. A model of the Forbush-type decrease is proposed to explain the observed radial dependence of the recovery time and time to minimum of the decrease. The implications of these results for understanding the relationship between Forbush-type decreases and the 11-year variation are discussed.

  9. A numerical investigation of planetesimal collision trajectories with a Moon accumulating in Earth orbit

    NASA Technical Reports Server (NTRS)

    Cox, L. P.

    1984-01-01

    In the scenario of lunar origin in which the Moon is assumed to have accreted most of its mass while in orbit about the Earth, ismals on the accrea knowledge of the relative impact rates of heliocentric planetting Earth and Moon is essential for any attempt to establish dynamical constraints on lunar origin. Numerical integrations of the regularized equations of motion for four bodies (Sun, Earth, Moon, planetismal) were done. A planetismal impact trajectory was calculated by assuming that the planetismal has hit the surface of the Moon at an assumed location, traveling in an assumed direction, and with an assumed impact speed. Next, the equations of motion were numerically integrated backward in time in order to determine from where the planetismal has come. In this way those volumes in heliocentric orbital element space which contribute trajectories that directly impact the Moon.

  10. Analysis and interpretation of CCD data on P/Halley and physical parameters and activity status of cometary nuclei at large heliocentric distance

    NASA Technical Reports Server (NTRS)

    Belton, Michael J. S.; Mueller, Beatrice

    1991-01-01

    The scientific objectives were as follows: (1) to construct a well sampled photometric time series of comet Halley extending to large heliocentric distances both post and pre-perihelion passage and derive a precise ephemeris for the nuclear spin so that the physical and chemical characteristics of individual regions of activity on the nucleus can be determined; and (2) to extend the techniques in the study of Comet Halley to the study of other cometary nuclei and to obtain new observational data.

  11. Emission band and continuum photometry of Comet West \\/1975n\\/. I - Heliocentric dependence of the flux in the emission bands and the continuum

    Microsoft Academic Search

    K. R. Sivaraman; G. S. D. Babu; M. K. V. Bappu; M. Parthasarathy

    1979-01-01

    Spectrum scans of the coma of Comet West (1975n) covering the range lambdalambda3700--5700 Å were made on eight nights when the heliocentric distance of the comet varied from 0.588 to 0.853 AU. These have been used to derive the absolute flux in the CN(0,0), C3(4050), C2(1, 0) and C2(0, 0) bands as well as in the continuum. Enhancements in the

  12. Orbital mechanics

    Microsoft Academic Search

    Vladimir A. Chobotov

    1991-01-01

    The present work on the 'applied', or engineering-related aspects of orbital mechanics gives attention to the geographic and azimuth-elevation coordinate systems, as well as their transformations; the orbital parameters of a satellite; the universal approach to a body's position and velocity as a function of time, and geodetic and geocentric altitudes; and such issues in orbital maneuvering as the general

  13. 29P/Schwassmann-Wachmann 1 --- orbital distribution of outbursts

    NASA Astrophysics Data System (ADS)

    Krisandova, Z.; Svoren, J.

    2014-07-01

    The orbital distribution of outbursts of brightness for the periodic comet 29P/Schwassmann-Wachmann 1 is studied. Despite the fact that the perihelion distance is 5.722 au, the comet exhibits an enhanced activity. We found a so far undiscovered significant result that the increased cometary activity starts on a pre-perihelion arc and continues after the aphelion passage in spite of the large heliocentric distance. We identified outbursts of comets in the publication of Kamel (1991), because this publication extends the series of records of the outbursts in the past. The publication of Kamel contains 78 outbursts including 3 overlapping with a catalog of ICQ, where we found 101 other outbursts and 9 outbursts were obtained from the data of Skalnate Pleso Observatory. Despite the large heliocentric distance and small difference between the aphelion and the perihelion distances (0.53 au), the obvious dependence on the gradual orbital approach of the comet was found. The enclosed figure (analogous to Hughes, 1975) shows the positions of 29P/Schwassmann- Wachmann 1 around its orbit at the time of the outbursts.

  14. In-Flight Operation of the Dawn Ion Propulsion System Through Orbit Capture at Vesta

    NASA Technical Reports Server (NTRS)

    Garner, Charles E.; Rayman, Marc D.; Brophy, John R.; Mikes, Steven C.

    2011-01-01

    The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from Cape Canaveral Air Force Station on September 27, 2007 on a Delta -II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218 kg spacecraft into an Earth-escape trajectory. Onboard the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide most of the ?V needed for heliocentric transfer to Vesta, orbit capture at Vesta, transfer among Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer among Ceres science orbits. The first 80 days after launch were dedicated to the initial checkout of the spacecraft which was followed by about ten months of full-power thrusting leading to a Mars gravity assist in February 2009 that provided 1 km/s of heliocentric energy increase and is the only part of the mission following launch in which a needed velocity change is not accomplished by the IPS. Deterministic thrusting for heliocentric transfer to Vesta resumed in June 2009 and was concluded with orbit capture at Vesta in July 2011. IPS was operated for approximately 23,400 hours, consumed approximately 250 kg of xenon, and provided a delta-V of approximately 6.7 km/s to achieve orbit capture at Vesta. IPS performance characteristics are very close to the expected performance characteristics based on analysis performed pre-launch. The only significant problem to have occurred over the almost four years of IPS operations in flight was the temporary failure of a valve driver board in DCIU-1, resulting in a loss of thrust of approximately 29 hours. Thrusting operations resumed after switching to DCIU-2, and power cycling conducted after orbit capture indicates DCIU-1 is completely operational. After about three weeks of survey operations IPS will be used to maneuver the spacecraft as needed for science operations including orbit transfers. After approximately one year of science operations IPS will then be used for escape from Vesta and begin thrusting for cruise to Ceres with a planned arrival date at Ceres in February 2015. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through orbit capture and the start of science operations at Vesta.

  15. Pupils Produce their Own Narratives Inspired by the History of Science: Animation Movies Concerning the Geocentric-Heliocentric Debate

    NASA Astrophysics Data System (ADS)

    Piliouras, Panagiotis; Siakas, Spyros; Seroglou, Fanny

    2011-07-01

    In this paper, we present the design and application of a teaching scenario appropriate for 12-years-old pupils in the primary school aiming to a better understanding of scientific concepts and scientific methods, linking the development of individual thinking with the development of scientific ideas and facilitating a better understanding of the nature of science. The design of the instructional material supporting this scenario has been based on the study of the history of astronomy and especially on: (a) The various theories concerning the movement of Earth, our solar system and the universe. (b) Key-stories highlighting the evolutionary character of scientific knowledge as well as the cultural interrelations of science and society. The design of the teaching scenario has focused on the participation of pupils in gradually evolving discourses and practices encouraging an appreciation of aspects of the nature of science (e.g. the role of observation and hypothesis, the use of evidence, the creation and modification of models). In this case, pupils are asked to produce their own narratives: animation movies concerning the geocentric-heliocentric debate inspired by the history of science, as the animation technique presents strong expressional potential and currently has many applications in the field of educational multimedia. The research design of this current case study has been based on the SHINE research model, while data coming from pupils' animation movies, questionnaires, interviews, worksheets, story-boards and drawings have been studied and analyzed using the GNOSIS research model. Elaborated data coming from our analysis approach reveal the appearance, transformation and evolution of aspects of nature of science appreciated by pupils and presented in their movies. Data analysis shows that during the application pupils gradually consider more and more the existence of multiple answers in scientific questions, appreciate the effect of culture on the way science functions and the way scientists work as well as the effect of new scientific interpretations that replace the old ones in the light of new evidence. The development of pupils' animation movies carrying aspects of the history of astronomy with a strong focus on the understanding of the nature of science creates a dynamic educational environment that facilitates pupils' introduction to a demanding teaching content (e.g. planet, model, retrograde motion) placing it in context (key-stories from the history of science) and at the same time offers to pupils the opportunity to engage their personal habits, interests and hobbies in the development of their science movies.

  16. Orbital Decompression

    MedlinePLUS

    ... treat a variety of eye related diseases. The orbit (eye socket) is a space within your skull that ... has then effectively enlarged the space of the orbit which in turn “decompresses” the entire eye. At the end of the surgery, there is ...

  17. Heliocentric Distance of Coronal Mass Ejections at the Time of Energetic Particle Release: Revisiting the Ground Level Enhancement Events of Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2011-01-01

    Using the kinematics of coronal mass ejections (CMEs), onset time of soft X-ray flares, and the finite size of the pre-eruption CME structure, we derive the heliocentric distane at which the energetic particles during the ground level enhancement (GLE) events of Solar Cycle 23. We find that the GLE particles are released when the CMEs reach an average heliocentric distance of approx.3.25 solar radii (Rs). From this we infer that the shocks accelerating the particles are located at similar heights. Type II radio burst observations indicate that the CMEs are at much lower distances (average approx.1.4 Rs) when the CME-driven shock first forms. The shock seems to travel approx.1.8 Rs over a period of approox.30 min on the average before releasing the GLE particles. In deriving these results, we made three assumptions that have observational support: (i) the CME lift off occurs from an initial distance of about 1.25 Rs; (ii) the flare onset and CME onset are one and the same because these are two different manifestations of the same eruption; and (iii) the CME has positive acceleration from the onset to the first appearance in the coronagraphic field of view (2.5 to 6 Rs). Observations of coronal cavities in eclipse pictures and in coronagraphic images justify the assumption (i). The close relationship between the flare reconnection magnetic flux and the azimuthal flux of interplanetary magnetic clouds justify assumption (ii) consistent with the standard model (CSHKP) of solar eruption. Coronagraphic observations made close to the solar surface indicate a large positive acceleration of CMEs to a heliocentric distance of approx.3 Rs before they start slowing down due to the drag force. The inferred acceleration (approx.1.5 km/s/s) is consistent with reported values in the literature.

  18. Latitude variation of recurrent MeV-energy proton flux enhancements in the heliocentric radial range 11 to 20 AU and possible correlation with solar coronal hole dynamics

    NASA Technical Reports Server (NTRS)

    Christon, S. P.; Stone, E. C.

    1985-01-01

    Recurrent low energy (not less than 0.5 MeV) proton flux enhancements, reliable indicators of corotating plasma interaction regions in interplanetary space, have been observed on the Voyager 1 and 2 and Pioneer 11 spacecraft in the heliographic latitude range 2 deg S to 23 deg N and the heliocentric radial range 11 to 20 AU. After a period of rather high correlation between fluxes at different latitudes in early 1983, distinct differences develop. The evolution of the fluxes appears to be related to the temporal and latitudinal dynamics of solar coronal holes, suggesting that information about the latitudinal structure of solar wind stream sources propagates to these distances.

  19. Data catalog series for space science and applications flight missions. Volume 1A: Descriptions of planetary and heliocentric spacecraft and investigations, second edition

    NASA Technical Reports Server (NTRS)

    Cameron, Winifred Sawtell (editor); Vostreys, Robert W. (editor)

    1988-01-01

    The main purpose of the data catalog series is to provide descriptive references to data generated by space science flight missions. The data sets described include all of the actual holdings of the Space Science Data Center (NSSDC), all data sets for which direct contact information is available, and some data collections held and serviced by foreign investigators, NASA and other U.S. government agencies. This volume contains narrative descriptions of planetary and heliocentric spacecraft and associated experiments. The following spacecraft series are included: Mariner, Pioneer, Pioneer Venus, Venera, Viking, Voyager, and Helios. Separate indexes to the planetary and interplanetary missions are also included.

  20. Space-based Search for Transiting Exoplanets Orbiting Bright Stars

    NASA Astrophysics Data System (ADS)

    Tsvetanov, Zlatan

    At the current stage of research transiting planets hold the key to advancing our knowledge of exoplanets as they are the only targets that allow determination of many of the key plane-tary parameters. Because the employed techniques are differential (either photometry or spec-troscopy) and the planet is significantly fainter the host star the dominant limitation is simply the number of photons. This puts a very high premium on transiting planets with bright parent stars. The ExoPlanet Task Force recognized the high value of planets transiting bright stars and identified the need to perform a wide area space-based transit survey. In this presentation I will describe a program that addresses the ExoPTF recommendation by using the output of one of the instruments on the currently operating space mission STEREO. STEREO is the third mission in NASA's Solar Terrestrial Probes program. It uses two nearly identical spacecrafts -one on an Earth-leading orbit and one on an Earth-trailing orbit -each equipped with a suit of five small telescopes to provide a stereoscopic view of the coronal mass ejections (CME) as they propagate away from the Sun. As each of these telescopes observes a portion of the heliospehre, they also image the star field in the background. For the purposes of this study we will consider only the images obtained by the HI-1 instruments. Other instruments, although showing the stellar background as well, do not have the data output suitable for a search for transiting exoplanets. This project described here has the potential of delivering a number of very high value targets for follow-up studies with a wide range of facilities, both ground-based and space-based. It will provide a complete survey of all bright stars (<10m) for 18% of the sky. The photometric data series have the sensitivity to detect all transiting hot-Jupiters and other gas giants with periods up to ˜20 days and even some Neptune size planets orbiting bright and/or late type stars. On the extreme bright end, the survey is sensitive to some super-Earth size planets, but the available number of target stars is small. In my presentation I will describe the capabilities and limitations of the project, will demon-strate the utility of the HI-1 images for searching for transiting exoplanets, and will describe the existing data for several RV discovered planets.

  1. Orbital Dynamics

    NSDL National Science Digital Library

    This video from SpaceTEC National Aerospace Technical Education Center explains the mechanics of orbital dynamics and Newton's first law of motion. This three minute video is one of the aerospace certification readiness courses.

  2. Nuclear reactor power for an electrically powered orbital transfer vehicle

    SciTech Connect

    Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Fujita, T.; Grossman, M.; Kia, T.; Nesmith, B.

    1987-01-01

    To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined which utilize electric propulsion and this nuclear reactor power for multiple transfers of cargo between low Earth orbit (LEO) and geosynchronous Earth orbit (GEO). A propulsion system employing ion thrusters and xenon propellant was selected. Propellant and thrusters are replaced after each sortie to GEO. The mass of the Orbital Transfer Vehicle (OTV), empty and dry, is 11,000 kg; nominal propellant load is 5000 kg. The OTV operates between a circular orbit at 925 km altitude, 28.5 deg inclination, and GEO. Cargo is brought to the OTV by Shuttle and an Orbital Maneuvering Vehicle (OMV); the OTV then takes it to GEO. The OTV can also bring cargo back from GEO, for transfer by OMV to the Shuttle. OTV propellant is resupplied and the ion thrusters are replaced by the OMV before each trip to GEO. At the end of mission life, the OTV's electric propulsion is used to place it in a heliocentric orbit so that the reactor will not return to Earth. The nominal cargo capability to GEO is 6000 kg with a transit time of 120 days; 1350 kg can be transferred in 90 days, and 14,300 kg in 240 days. These capabilities can be considerably increased by using separate Shuttle launches to bring up propellant and cargo, or by changing to mercury propellant.

  3. Nuclear reactor power for an electrically powered orbital transfer vehicle

    NASA Technical Reports Server (NTRS)

    Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Fujita, T.; Grossman, M.; Kia, T.; Nesmith, B.

    1987-01-01

    To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined which utilize electric propulsion and this nuclear reactor power for multiple transfers of cargo between low earth orbit (LEO) and geosynchronous earth orbit (GEO). A propulsion system employing ion thrusters and xenon propellant was selected. Propellant and thrusters are replaced after each sortie to GEO. The mass of the Orbital Transfer Vehicle (OTV), empty and dry, is 11,000 kg; nominal propellant load is 5000 kg. The OTV operates between a circular orbit at 925 km altitude, 28.5 deg inclination, and GEO. Cargo is brought to the OTV by Shuttle and an Orbital Maneuvering Vehicle (OMV); the OTV then takes it to GEO. The OTV can also bring cargo back from GEO, for transfer by OMV to the Shuttle. OTV propellant is resupplied and the ion thrusters are replaced by the OMV before each trip to GEO. At the end of mission life, the OTV's electric propulsion is used to place it in a heliocentric orbit so that the reactor will not return to earth. The nominal cargo capability to GEO is 6000 kg with a transit time of 120 days; 1350 kg can be transferred in 90 days, and 14,300 kg in 240 days. These capabilities can be considerably increased by using separate Shuttle launches to bring up propellant and cargo, or by changing to mercury propellant.

  4. Orbit Determination Accuracy for Comets on Earth-Impacting Trajectories

    NASA Technical Reports Server (NTRS)

    Kay-Bunnell, Linda

    2004-01-01

    The results presented show the level of orbit determination accuracy obtainable for long-period comets discovered approximately one year before collision with Earth. Preliminary orbits are determined from simulated observations using Gauss' method. Additional measurements are incorporated to improve the solution through the use of a Kalman filter, and include non-gravitational perturbations due to outgassing. Comparisons between observatories in several different circular heliocentric orbits show that observatories in orbits with radii less than 1 AU result in increased orbit determination accuracy for short tracking durations due to increased parallax per unit time. However, an observatory at 1 AU will perform similarly if the tracking duration is increased, and accuracy is significantly improved if additional observatories are positioned at the Sun-Earth Lagrange points L3, L4, or L5. A single observatory at 1 AU capable of both optical and range measurements yields the highest orbit determination accuracy in the shortest amount of time when compared to other systems of observatories.

  5. Orbital Debris

    NASA Technical Reports Server (NTRS)

    Kessler, D. J. (compiler); Su, S. Y. (compiler)

    1985-01-01

    Earth orbital debris issues and recommended future activities are discussed. The workshop addressed the areas of environment definition, hazards to spacecraft, and space object management. It concluded that orbital debris is a potential problem for future space operations. However, before recommending any major efforts to control the environment, more data are required. The most significant required data are on the population of debris smaller than 4 cm in diameter. New damage criteria are also required. When these data are obtained, they can be combined with hypervelocity data to evaluate the hazards to future spacecraft. After these hazards are understood, then techniques to control the environment can be evaluated.

  6. Elliptical Orbits

    NSDL National Science Digital Library

    Michael Horton

    2009-05-30

    Although not inquiry, this activity is important for students to understand what an ellipse is and what a focus is, and to break misconceptions about Earth's orbit being highly elliptical. This is the perfect place to check to see if students have the mis

  7. Orbital Mechanics.

    ERIC Educational Resources Information Center

    Dalton, Joel B.

    Three computer programs are presented that allow the high school student to explore and understand the physical forces involved in orbital flight at a greater depth than is usually possible. For each program, introductory material is given including the physics and mathematics involved. This is followed by the computer program in BASIC language.…

  8. Eye and orbit ultrasound

    MedlinePLUS

    Echography - eye orbit; Ultrasound - eye orbit; Ocular ultrasonography; Orbital ultrasonography ... ophthalmology department of a hospital or clinic. Your eye is numbed with medicine (anesthetic drops). The ultrasound ...

  9. Orbiting Hotel

    NSDL National Science Digital Library

    Mrs. Hicken

    2009-10-19

    It is the year 2025 and a large company, Z-Tech, wants to put a hotel in space having it orbit around one of the planets in our solar system. Our 9th grade class has been given a very important job. We have to search for the perfect location for the hotel. Our job is to report back to the company with the planet that is the best place for an orbiting hotel. The Task: You are to write a report recommending which planet should be chosen. Your report should include pictures of the planet you recommended. Here are the questions you should answer in order to report back to Z-Tech with your recommendation. * Which planet will be the ...

  10. Shapes of d Orbitals

    NSDL National Science Digital Library

    Shapes of d Orbitals shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation.Shapes of d Orbitals has a link to D Orbitals in an Octahedral Ligand Field. Here the user may click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable. Orbital phase is shown by the different colors.

  11. NASA's Spitzer Space Telescope's Operational Mission Experience

    NASA Technical Reports Server (NTRS)

    Wilson, Robert K.; Scott, Charles P.

    2006-01-01

    New Generation of Detector Arrays(100 to 10,000 Gain in Capability over Previous Infrared Space Missions). IRAC: 256 x 256 pixel arrays operating at 3.6 microns, 4.5 microns, 5.8 microns, 8.0 microns. MIPS: Photometer with 3 sets of arrays operating at 24 microns, 70 microns and 160 microns. 128 x 128; 32 x 32 and 2 x 20 arrays. Spectrometer with 50-100 micron capabilities. IRS: 4 Array (128x128 pixel) Spectrograph, 4 -40 microns. Warm Launch Architecture: All other Infrared Missions launched with both the telescope and scientific instrument payload within the cryostat or Dewar. Passive cooling used to cool outer shell to approx.40 K. Cryogenic Boil-off then cools telescope to required 5.5K. Earth Trailing Heliocentric Orbit: Increased observing efficiency, simplification of observation planning, removes earth as heat source.

  12. Reflection Model as Applied for the Analysis of Enhancements of Solar Cosmic Rays at Different Heliocentric Distances: An Example of the Event Observed in June 1991 onboard GRANAT and ULYSSES Spacecraft

    Microsoft Academic Search

    E. E. Grigorenko; G. P. Lyubimov

    2004-01-01

    In this paper we consider a large-scale enhancement of the intensity of solar protons (E = 1–20 MeV) observed in June 1991 for 26 days at different points of interplanetary space, onboard ULYSSES (in the time period under consideration it was located at a heliocentric distance of 3 AU, at an angular distance of ~70° to the East of the

  13. Heliocentric architecture : materializing solar cadences

    E-print Network

    Wastvedt, Trygve (Trygve Howard)

    2015-01-01

    There is a long tradition of architecture creating atmospheric, awe-inspiring experiences by shaping and making visible natural light. Another similarly long-established approach to daylighting optimizes lighting conditions ...

  14. Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the LADEE Spacecraft

    NASA Technical Reports Server (NTRS)

    Genova, A. L.

    2014-01-01

    This paper presents results from a contingency trajectory analysis performed for the Lunar Atmosphere & Dust Environment Explorer (LADEE) mission in the event of a missed lunar-orbit insertion (LOI) maneuver by the LADEE spacecraft. The effects of varying solar perturbations in the vicinity of the weak stability boundary (WSB) in the Sun-Earth system on the trajectory design are analyzed and discussed. It is shown that geocentric recovery trajectory options existed for the LADEE spacecraft, depending on the spacecraft's recovery time to perform an Earth escape-prevention maneuver after the hypothetical LOI maneuver failure and subsequent path traveled through the Sun-Earth WSB. If Earth-escape occurred, a heliocentric recovery option existed, but with reduced science capacapability for the spacecraft in an eccentric, not circular near-equatorial retrograde lunar orbit.

  15. Viking satellite orbit determination

    Microsoft Academic Search

    C. E. Hildebrand; E. J. Christensen; D. H. Boggs; G. H. Born; H. Hokikian; J. F. Jordan; W. B. Howard

    1977-01-01

    During the summer of 1976, the two Viking spacecraft, each consisting of an orbiter-lander combination, were inserted into orbit about Mars. The paper describes the experiences of the Viking Satellite Orbit Determination Team in determining Mars centered ephemerides of the orbiters and positions of the landers from the two-way Doppler and range data, and synthesizes the different phases of the

  16. Rock-Around Orbits

    E-print Network

    Bourgeois, Scott K.

    2010-07-14

    with larger orbits far above the Earth's surface, e.g. a Geostationary Orbit. Camera systems mounted on satellites can provide an eff ective way to observe these objects. Using a satellite with a speci c orbit relative to the RSO's orbit, one can passively...

  17. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    Results from operational OD produced by the NASA Goddard Flight Dynamics Facility for the LRO nominal and extended mission are presented. During the LRO nominal mission, when LRO flew in a low circular orbit, orbit determination requirements were met nearly 100% of the time. When the extended mission began, LRO returned to a more elliptical frozen orbit where gravity and other modeling errors caused numerous violations of mission accuracy requirements. Prediction accuracy is particularly challenged during periods when LRO is in full-Sun. A series of improvements to LRO orbit determination are presented, including implementation of new lunar gravity models, improved spacecraft solar radiation pressure modeling using a dynamic multi-plate area model, a shorter orbit determination arc length, and a constrained plane method for estimation. The analysis presented in this paper shows that updated lunar gravity models improved accuracy in the frozen orbit, and a multiplate dynamic area model improves prediction accuracy during full-Sun orbit periods. Implementation of a 36-hour tracking data arc and plane constraints during edge-on orbit geometry also provide benefits. A comparison of the operational solutions to precision orbit determination solutions shows agreement on a 100- to 250-meter level in definitive accuracy.

  18. Interactive Molecular Orbitals

    NSDL National Science Digital Library

    The majority of Introductory Chemistry texts provide students with an adequate introduction to the visual aspects of the molecular orbital model for homonuclear diatomic molecules. The treatment of heteronuclear diatomic and polyatomic molecules is less uniform. Heteronuclear diatomics, when mentioned, are invariably treated as being derived from homonuclear diatomics. While the atomic orbital energy level differences in heteronuclear diatomics is sometimes pictured, the consequences of those differences for the resultant molecular orbitals are rarely discussed. The discussion of polyatomic molecular orbitals in these texts is limited to showing that parallel p-orbitals produce delocalized pi molecular orbitals. The molecules typically mentioned in this context are benzene, nitrate ion and carbonate ion. However, It is rarely pointed out that the six p-orbitals in benzene would form 6 pi molecular orbitals, and that only one of these orbitals would look like the picture in the text.These interactive modules are designed to clarify this subject.

  19. The Space InfraRed Telescope Facility (SIRTF) 1 Science Objectives of the SIRTF Mission

    E-print Network

    Linsky, Jeffrey L.

    mass than is needed to sustain core hydrogen burning; T dwarfs; L dwarfs; cloudy atmospheres with mole­ cules like methane and ammonia; initial mass function at the low mass end; can brown dwarfs explain Instrument Description 2.1 Observatory ffl Launched on 25 August 2003 into an Earth­trailing heliocentric

  20. Lunar orbiting prospector

    NASA Technical Reports Server (NTRS)

    1988-01-01

    One of the prime reasons for establishing a manned lunar presence is the possibility of using the potential lunar resources. The Lunar Orbital Prospector (LOP) is a lunar orbiting platform whose mission is to prospect and explore the Moon from orbit in support of early lunar colonization and exploitation efforts. The LOP mission is divided into three primary phases: transport from Earth to low lunar orbit (LLO), operation in lunar orbit, and platform servicing in lunar orbit. The platform alters its orbit to obtain the desired surface viewing, and the orbit can be changed periodically as needed. After completion of the inital remote sensing mission, more ambitious and/or complicated prospecting and exploration missions can be contemplated. A refueled propulsion module, updated instruments, or additional remote sensing packages can be flown up from the lunar base to the platform.

  1. Tuberculoma of orbit.

    PubMed

    Mehra, K S; Pattanayak, S P; Saroj, G

    1992-01-01

    An interesting case of tuberculoma of the orbit, involving the whole of the eyeball with other orbital cavity structures, is being presented. This is very rarely seen in clinical practice. PMID:1302233

  2. Orbital Mechanics Analysis Program

    NASA Technical Reports Server (NTRS)

    Simon, W. C.; Jankowski, S. C.; Hughes, T. B.

    1985-01-01

    Orbital Mechanics Analysis Program provides engineers with simple tool for analysis or synthesis of any orbital maneuvering function involving vehicle and target. Program useful in such applications as proximity operations and rendezvous maneuvers.

  3. MIRO: Microwave Instrument for Rosetta Orbiter

    NASA Astrophysics Data System (ADS)

    Gulkis, S.; Frerking, M.; Crovisier, J.; Beaudin, G.; Hartogh, P.; Encrenaz, P.; Koch, T.; Kahn, C.; Salinas, Y.; Nowicki, R.; Irigoyen, R.; Janssen, M.; Stek, P.; Hofstadter, M.; Allen, M.; Backus, C.; Kamp, L.; Jarchow, C.; Steinmetz, E.; Deschamps, A.; Krieg, J.; Gheudin, M.; Bockelée-Morvan, D.; Biver, N.; Encrenaz, T.; Despois, D.; Ip, W.; Lellouch, E.; Mann, I.; Muhleman, D.; Rauer, H.; Schloerb, P.; Spilker, T.

    2007-02-01

    The European Space Agency Rosetta Spacecraft, launched on March 2, 2004 toward Comet 67P/Churyumov-Gerasimenko, carries a relatively small and lightweight millimeter-submillimeter spectrometer instrument, the first of its kind launched into deep space. The instrument will be used to study the evolution of outgassing water and other molecules from the target comet as a function of heliocentric distance. During flybys of the asteroids (2867) Steins and (21) Lutetia in 2008 and 2010 respectively, the instrument will measure thermal emission and search for water vapor in the vicinity of these asteroids. The instrument, named MIRO (Microwave Instrument for the Rosetta Orbiter), consists of a 30-cm diameter, offset parabolic reflector telescope followed by two heterodyne receivers. Center-band operating frequencies of the receivers are near 190 GHz (1.6 mm) and 562 GHz (0.5 mm). Broadband continuum channels are implemented in both frequency bands for the measurement of near surface temperatures and temperature gradients in Comet 67P/Churyumov-Gerasimenko and the asteroids (2867) Steins and (21) Lutetia. A 4096 channel CTS (Chirp Transform Spectrometer) spectrometer having 180 MHz total bandwidth and 44 kHz resolution is, in addition to the continuum channel, connected to the submillimeter receiver. The submillimeter radiometer/spectrometer is fixed tuned to measure four volatile species CO, CH3OH, NH3 and three, oxygen-related isotopologues of water, H2 16O, H2 17O and H2 18O. The basic quantities measured with the MIRO instrument are surface temperature, gas production rates and relative abundances, and velocity and excitation temperature of each species, along with their spatial and temporal variability. This paper provides a short discussion of the scientific objectives of the investigation, and a detailed discussion of the MIRO instrument system.

  4. SEASAT B orbit synthesis

    NASA Technical Reports Server (NTRS)

    Rea, F. G.; Warmke, J. M.

    1976-01-01

    Addition were made to Battelle's Interactive Graphics Orbit Selection (IGOS) program; IGOS was exercised via telephone lines from JPL, and candidate SEASAT orbits were analyzed by Battelle. The additions to the program enable clear understanding of the implications of a specific orbit to the diverse desires of the SEASAT user community.

  5. Everything in OrbitEverything in Orbit Orbital VelocityOrbital Velocity

    E-print Network

    Herrick, Robert R.

    , it would crash into the Sunenergy, it would crash into the Sun #12;Application: satellitesApplication: satellites We can put satellites in any orbit around the Earth, but inertia We can put satellites in any gravitational force to keep it in orbit That means closer satellites must orbit the Earth That means closer

  6. Five Equivalent d Orbitals

    ERIC Educational Resources Information Center

    Pauling, Linus; McClure, Vance

    1970-01-01

    Amplifies and clarifies a previous paper on pyramidal d orbitals. Discusses two sets of pyramid d orbitals with respect to their maximum bond strength and their symmetry. Authors described the oblate and prolate pentagonal antiprisms arising from the two sets of five equivalent d orbitals. (RR)

  7. Rock-Around Orbits 

    E-print Network

    Bourgeois, Scott K.

    2010-07-14

    me to be a better engineer and to persist because there is always an answer. I would also like to thank the sta at the Spacecraft Technology Center for their help and support. I have learned that patience is not only a good virtue to have as a person... of Minimum Distance from Spacecraft to Circular Target Orbit 16 10 Minimum Distance between RAO and GEO Orbits for One RAO Orbital Period (Example 1) : : : : : : : : : : : : : : : : : : : : : : : 17 11 Compatible Orbits for Elliptical Target Orbit (Example 2...

  8. OTV orbital tanking systems

    NASA Technical Reports Server (NTRS)

    Heald, D. A.; Merino, F.

    1979-01-01

    Orbital transfer of cryogenic propellants could benefit spacecraft and Orbital Transfer Vehicle (OTV) missions in the 1980s by supplying main propulsion, attitude control, or other fluid systems. The Space Shuttle can operate as a tanker when equipped with cryogenic propellant storage and orbital transfer systems. The key technologies are multilayer insulation, capillary propellant acquisition, zero-g gaging, orbital chilldown, and possibly large flight weight dewars. The technologies and operations could be realistically demonstrated using a Centaur that has been integrated with the Shuttle. Orbital refueling capability can enhance the usefulness of the whole Shuttle program

  9. Orbit correction in an orbit separated cyclotron

    NASA Astrophysics Data System (ADS)

    Plostinar, C.; Rees, G. H.

    2014-04-01

    The orbit separated proton cyclotron (OSC) described in [1] differs in concept from that of a separated orbit cyclotron (SOC) [2]. Synchronous acceleration in an OSC is based on harmonic number jumps and orbit length adjustments via reverse bending. Four-turn acceleration in the OSC enables it to have four times fewer cryogenic-cavity systems than in a superconducting linac of the same high beam power and energy range. Initial OSC studies identified a progressive distortion of the spiral beam orbits by the off-axis, transverse deflecting fields in its accelerating cavities. Compensation of the effects of these fields involves the repeated use of a cavity field map, in a 3-D linac tracking code, to determine the modified arc bends required for the OSC ring. Subsequent tracking studies confirm the compensation scheme and show low emittance growth in acceleration.

  10. Lunar Reconnaissance Orbiter Orbit Determination Accuracy Analysis

    NASA Technical Reports Server (NTRS)

    Slojkowski, Steven E.

    2014-01-01

    LRO definitive and predictive accuracy requirements were easily met in the nominal mission orbit, using the LP150Q lunar gravity model. center dot Accuracy of the LP150Q model is poorer in the extended mission elliptical orbit. center dot Later lunar gravity models, in particular GSFC-GRAIL-270, improve OD accuracy in the extended mission. center dot Implementation of a constrained plane when the orbit is within 45 degrees of the Earth-Moon line improves cross-track accuracy. center dot Prediction accuracy is still challenged during full-Sun periods due to coarse spacecraft area modeling - Implementation of a multi-plate area model with definitive attitude input can eliminate prediction violations. - The FDF is evaluating using analytic and predicted attitude modeling to improve full-Sun prediction accuracy. center dot Comparison of FDF ephemeris file to high-precision ephemeris files provides gross confirmation that overlap compares properly assess orbit accuracy.

  11. What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?

    E-print Network

    Lorenzo Iorio; Giuseppe Giudice

    2006-04-01

    In this paper we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20 AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20 AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of 8.74\\times 10^-10 m s^-2, would affect their orbits with secular and short-period signals large enough to be detected according to the latest published results by E.V. Pitjeva, even by considering errors up to 30 times larger than those released. The absence of such anomalous signatures in the latest data rules out the possibility that in the region 20-40 AU of the Solar System an anomalous force field inducing a constant and radial acceleration with those characteristics affects the motion of the major planets.

  12. Orbit Determination of the Lunar Reconnaissance Orbiter

    NASA Technical Reports Server (NTRS)

    Mazarico, Erwan; Rowlands, D. D.; Neumann, G. A.; Smith, D. E.; Torrence, M. H.; Lemoine, F. G.; Zuber, M. T.

    2011-01-01

    We present the results on precision orbit determination from the radio science investigation of the Lunar Reconnaissance Orbiter (LRO) spacecraft. We describe the data, modeling and methods used to achieve position knowledge several times better than the required 50-100m (in total position), over the period from 13 July 2009 to 31 January 2011. In addition to the near-continuous radiometric tracking data, we include altimetric data from the Lunar Orbiter Laser Altimeter (LOLA) in the form of crossover measurements, and show that they strongly improve the accuracy of the orbit reconstruction (total position overlap differences decrease from approx.70m to approx.23 m). To refine the spacecraft trajectory further, we develop a lunar gravity field by combining the newly acquired LRO data with the historical data. The reprocessing of the spacecraft trajectory with that model shows significantly increased accuracy (approx.20m with only the radiometric data, and approx.14m with the addition of the altimetric crossovers). LOLA topographic maps and calibration data from the Lunar Reconnaissance Orbiter Camera were used to supplement the results of the overlap analysis and demonstrate the trajectory accuracy.

  13. Orbital granulocytic sarcoma

    PubMed Central

    Stockl, F.; Dolmetsch, A.; Saornil, M; Font, R.; Burnier, M.

    1997-01-01

    AIM—Orbital granulocytic sarcoma is a localised tumour composed of cells of myeloid origin. Histological diagnosis can be difficult in patients with poorly differentiated orbital tumours and no evidence of systemic leukaemia. The naphthol AS-D chloracetate esterase (Leder stain) and immunohistochemical stains for lysozyme and MAC387 were used to determine the staining characteristics of these tumours. A case series of seven patients with orbital granulocytic sarcoma is presented.?METHODS—Seven patients with orbital granulocytic sarcoma were studied. Haematoxylin and eosin, Leder, and lysozyme stained sections were available in seven cases. Unstained formalin fixed paraffin embedded sections of seven cases were available for immunohistochemical evaluation using the avidin-biotin-complex technique for MAC387.?RESULTS—The mean age of presentation of the orbital tumour was 8.8 years. Four patients presented with an orbital tumour before any systemic manifestations of leukaemia. In two cases the diagnosis of the orbital tumour and systemic leukaemia was made simultaneously. There was one case of established systemic myeloid leukaemia in remission with the subsequent development of orbital granulocytic sarcoma. Six of seven cases (86%) were positive for the Leder stain. Five of seven cases (71%) showed positive immunoreactivity with lysozyme. The immunohistochemical stain for MAC387 was positive in all seven cases (100%) including one case that was negative for both lysozyme and Leder stains.?CONCLUSIONS—Orbital granulocytic sarcoma is a tumour that affects children and can present with rapidly progressive proptosis. This tumour may develop before, during, or after the occurrence of systemic leukaemia. The combination of Leder and lysozyme stains is useful in the diagnosis of orbital granulocytic sarcoma. MAC387 may be a more reliable marker for orbital granulocytic sarcoma.?? PMID:9497470

  14. Viking Orbiter stereophotogrammetry

    Microsoft Academic Search

    M. Benesh

    1978-01-01

    Orbit characteristics of the two Viking Orbiter spacecraft made possible the acquisition of high-resolution imagery of the Martian surface, resulting in many excellent convergent stereopairs. Evaluation of these stereopairs presented a few unconventional problems because the routine relative orientation was not feasible, mainly due to a lack of good passpoints and to the technical peculiarities of TV vidicon imaging techniques.

  15. From surface to orbit

    Microsoft Academic Search

    Andras Bela Olah

    2011-01-01

    Space travel is highly expensive and has significant limitations. Among all space activities the process of travelling from the surface to orbit requires the greatest amount of energy, materials and cost. Basically even today, more than 61 years after the first artificial satellite was set to orbit, these difficulties have been the greatest barriers of the dawn of the real

  16. Orbits R Us!

    NSDL National Science Digital Library

    This site introduces the principle of geosynchronous orbits and geostationary weather satellites in non-technical terms. Several animations show how they work. The GOES (Geostationary Operational Environmental Satellite) and POES (Polar-orbiting Operational Environmental Satellites) satellite programs at NASA and NOAA are briefly explained.

  17. Orbital Shape Representations.

    ERIC Educational Resources Information Center

    Kikuchi, Osamu; Suzuki, Keizo

    1985-01-01

    Discusses the use of orbital shapes for instructional purposes, emphasizing that differences between polar, contour, and three-dimensional plots must be made clear to students or misconceptions will occur. Also presents three-dimensional contour surfaces for the seven 4f atomic orbitals of hydrogen and discusses their computer generation. (JN)

  18. Titan Orbiter Aerorover Mission

    NASA Technical Reports Server (NTRS)

    Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

    2001-01-01

    We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

  19. Analyzing Shuttle Orbiter Trajectories

    NASA Technical Reports Server (NTRS)

    Lear, W. M.

    1986-01-01

    LRBET4 program best-estimated-of-trajectory (BET) calculation for post-flight trajectory analysis of Shuttle orbiter. Produces estimated measurements for comparing predicted and actual trajectory of Earth-orbiting spacecraft. Kalman filter and smoothing filter applied to input data to estimate state vector, reduce noise, and produce BET. LRBET4 written in FORTRAN IV for batch execution.

  20. Mars Climate Orbiter

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The purpose of this mission is to study the climate history and the water distribution of Mars. Beautiful panoramic views of the shuttle on the launch pad, engine ignition, Rocket launch, and the separation and burnout of the Solid Rocket Boosters are shown. The footage also includes an animation of the mission. Detailed views of the path that the Orbiter traversed were shown. Once the Orbiter lands on the surface of Mars, it will dig a six to eight inch hole and collect samples from the planets' surface. The animation also included the prospective return of the Orbiter to Earth over the desert of Utah. The remote sensor on the Orbiter helps in finding the exact location of the Orbiter so that scientists may collect the sample and analyze it.

  1. Orbital Debris Mitigation

    NASA Technical Reports Server (NTRS)

    Kelley, R. L.; Jarkey, D. R.; Stansbery, G.

    2014-01-01

    Policies on limiting orbital debris are found throughout the US Government, many foreign space agencies, and as adopted guidelines in the United Nations. The underlying purpose of these policies is to ensure the environment remains safe for the operation of robotic and human spacecraft in near- Earth orbit. For this reason, it is important to consider orbital debris mitigation during the design of all space vehicles. Documenting compliance with the debris mitigation guidelines occurs after the vehicle has already been designed and fabricated for many CubeSats, whereas larger satellites are evaluated throughout the design process. This paper will provide a brief explanation of the US Government Orbital Debris Mitigation Standard Practices, a discussion of international guidelines, as well as NASA's process for compliance evaluation. In addition, it will discuss the educational value of considering orbital debris mitigation requirements as a part of student built satellite design.

  2. Orbital Causes of Incomitant Strabismus

    PubMed Central

    Lueder, Gregg T.

    2015-01-01

    Strabismus may result from abnormal innervation, structure, or function of the extraocular muscles. Abnormalities of the orbital bones or masses within the orbit may also cause strabismus due to indirect effects on the extraocular muscles. This paper reviews some disorders of the orbit that are associated with strabismus, including craniofacial malformations, orbital masses, trauma, and anomalous orbital structures. PMID:26180465

  3. Orbit Stabilization of Nanosat

    SciTech Connect

    JOHNSON,DAVID J.

    1999-12-01

    An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.

  4. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  5. OL- ORBITAL LIFETIME PROGRAM

    NASA Technical Reports Server (NTRS)

    Orr, L. H.

    1994-01-01

    The Orbital Lifetime (OL) program analyzes the long-term motion of Earth-orbiting spacecraft at altitudes of up to 2500 kilometers. It models perturbations to the orbit caused by solar radiation pressure, atmospheric drag, and gravitational effects due to the sun, the moon, and Earth oblateness. OL can be used to predict the orbital lifetime and decay rate of a satellite. The atmospheric density models used in OL are the U.S. Standard Atmosphere for altitudes below 90 km and the Jacchia model for altitudes above 90 km. The Jacchia model requires solar flux and geomagnetic index for the date of orbit. An input file containing these values for 1984 to 1998 is supplied with the OL package. The solar radiation pressure calculations in OL will predict the amount of time a spacecraft is subjected to the Earth's shadow. Input to OL includes spacecraft physical characteristics, initial orbit parameters, and launch date/time. OL calculates time histories of the orbital elements, total lifetime, and decay rates. A spacecraft is considered 'down' at an altitude of 64 km. OL also generates a file of plot data which can be input to a user-supplied graphics program for lifetime plots of altitude against time. OL is written in FORTRAN 77 for interactive or batch execution and has been implemented on a DEC VAX series computer operating under VMS. This program was developed in 1985.

  6. Visualization of atom's orbits.

    PubMed

    Kim, Byungwhan

    2014-02-01

    High-resolution imaging techniques have been used to obtain views of internal shapes of single atoms or columns of atoms. This review article focuses on the visualization of internal atomic structures such as the configurations of electron orbits confined to atoms. This is accomplished by applying visualization techniques to the reported images of atoms or molecules as well as static and dynamic ions in a plasma. It was found that the photon and electron energies provide macroscopic and microscopic views of the orbit structures of atoms, respectively. The laser-imaged atoms showed a rugged orbit structure, containing alternating dark and bright orbits believed to be the pathways for an externally supplied laser energy and internally excited electron energy, respectively. By contrast, the atoms taken by the electron microscopy provided a structure of fine electron orbits, systematically formed in increasing order of grayscale representing the energy state of an orbit. This structure was identical to those of the plasma ions. The visualized electronic structures played a critical role in clarifying vague postulates made in the Bohr model. Main features proposed in the atomic model are the dynamic orbits absorbing an externally supplied electromagnetic energy, electron emission from them while accompanying light radiation, and frequency of electron waves not light. The light-accompanying electrons and ionic speckles induced by laser light signify that light is composed of electrons and ions. PMID:24749452

  7. Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries

    NASA Astrophysics Data System (ADS)

    Grundy, William

    2007-07-01

    The recent discovery of numerous transneptunian binaries {TNBs} opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had their mutual orbits and separate colors determined, frustrating their use to investigate numerous important scientific questions. The current shortage of data especially cripples scientific investigations requiring statistical comparisons among the ensemble characteristics. We propose to obtain sufficient astrometry and photometry of 23 TNBs to compute their mutual orbits and system masses and to determine separate primary and secondary colors, roughly tripling the sample for which this information is known, as well as extending it to include systems of two near-equal size bodies. To make the most efficient possible use of HST, we will use a Monte Carlo technique to optimally schedule our observations.

  8. Orbit Determination Issues for Libration Point Orbits

    NASA Technical Reports Server (NTRS)

    Beckman, Mark; Bauer, Frank (Technical Monitor)

    2002-01-01

    Libration point mission designers require knowledge of orbital accuracy for a variety of analyses including station keeping control strategies, transfer trajectory design, and formation and constellation control. Past publications have detailed orbit determination (OD) results from individual notation point missions. This paper collects both published and unpublished results from four previous notation point missions (ISEE-3, SOHO, ACE and MAP) supported by Goddard Space Flight Center's Guidance, Navigation & Control Center. The results of those missions are presented along with OD issues specific to each mission. All past missions have been limited to ground based tracking through NASA ground sites using standard marine and Doppler measurement types. Advanced technology is enabling other OD options including onboard navigation using onboard attitude sensors and the use of the Very Long Baseline Interferometry (VLBI) measurement Delta Differenced One-Way Range (DDOR). Both options potentially enable missions to reduce coherent dedicated tracking passes while maintaining orbital accuracy. With the increased projected loading of the DSN, missions must find alternatives to the standard OD scenario.

  9. Gravitational interaction of planetesimals moving in close orbits

    NASA Astrophysics Data System (ADS)

    Ipatov, S. I.

    The orbital evolution of two gravitationally interacting objects (material-points) moving around the Sun is studied. These studies are based mainly on the results of numerical integration of the plane three-body problem. The following types of orbital evolution were considered: motion about triangular libration points on tadpole and horseshoe synod/c orbits (types M and N), the case of close approaches of the objects (type A), and chaotic variations of the orbital elements during which close approaches of the objects are impossible (type C). In the case of initially circular orbits with an initial angle fi_o=60 deg between the directions to the objects from the Sun vertex and 10^{-9} < mu < 2*10^{-4}, the maximum values of epsilon_o=(a_2-a_1)/a_1 that correspond to types N, M, A, and C were found to be equal to alpha=(1.63-l.64)mu^{1/2}, beta=(0.77-0.81)mu^{1/3}, gamma=(2.l-2.45)mu^{1/3}, and delta=(l.45-1.64)mu^{2/7}, respectively, where a_1 and a_2 are the initial values of the semimajor axes and mu is the ratio of the sum of the masses of the objects to the mass of the Sun. The values of alpha, beta, and delta are generally smaller for other values of fi_o. When epsilon_o=0, the smallest values of fi_o that correspond to types N and M are near 0.4 and 4*mu^{1/3} radian. The maximum eccentricities at mu_1orbital evolution of two, three, and one hundred gravitating objects (material points) moving around the Sun in initially eccentrical orbits, is studied numerically, mainly by the method of action spheres. It is demonstrated that in the case of three identical objects, maximum eccentricities can exceed those for two like objects by a factor of several tens. Typical variations in eccentricities of heliocentric orbits of objects while they are moving in a sphere of action are examined to reveal the dependence of their mean variations on the starting data, i.e., masses, eccentricities, and semimajor axes. The results of these examinations and analytical studies provide a basis for treating cases, where, in the course of the evolution of a disk comprising many small objects and that comprising a lesser number of more massive objects, the increments of average eccentricities are the same. The obtained results suggest that, due to their gravitational interaction, some bodies initially located beyond Neptune's orbit can migrate to this orbit.

  10. orbit.ps

    E-print Network

    consist of an arbitrary number of troughs are found numerically. The bifurca- ... Key words: water wave, Boussinesq system, traveling wave, homoclinic orbit,. multi-pulsed solution ... But to the best of my knowledge, there is no result regarding.

  11. Imaging in orbital trauma

    PubMed Central

    Lin, Ken Y.; Ngai, Philip; Echegoyen, Julio C.; Tao, Jeremiah P.

    2012-01-01

    Orbital trauma is one of the most common reasons for ophthalmology specialty consultation in the emergency department setting. We survey the literature from 1990 to present to describe the role of computed tomography (CT), magnetic resonance imaging (MRI) and their associated angiography in some of the most commonly encountered orbital trauma conditions. CT orbit can often detect certain types of foreign bodies, lens dislocation, ruptured globe, choroidal or retinal detachments, or cavernous sinus thrombosis and thus complement a bedside ophthalmic exam that can sometimes be limited in the setting of trauma. CT remains the workhorse for acute orbital trauma owing to its rapidity and ability to delineate bony abnormalities; however MRI remains an important modality in special circumstances such as soft tissue assessment or with organic foreign bodies. PMID:23961028

  12. Tethered orbital refueling study

    NASA Technical Reports Server (NTRS)

    Fester, Dale A.; Rudolph, L. Kevin; Kiefel, Erlinda R.; Abbott, Peter W.; Grossrode, Pat

    1986-01-01

    One of the major applications of the space station will be to act as a refueling depot for cryogenic-fueled space-based orbital transfer vehicles (OTV), Earth-storable fueled orbit maneuvering vehicles, and refurbishable satellite spacecraft using hydrazine. One alternative for fuel storage at the space station is a tethered orbital refueling facility (TORF), separated from the space station by a sufficient distance to induce a gravity gradient force that settles the stored fuels. The technical feasibility was examined with the primary focus on the refueling of LO2/LH2 orbital transfer vehicles. Also examined was the tethered facility on the space station. It was compared to a zero-gravity facility. A tethered refueling facility should be considered as a viable alternative to a zero-gravity facility if the zero-gravity fluid transfer technology, such as the propellant management device and no vent fill, proves to be difficult to develop with the required performance.

  13. Habitability study shuttle orbiter

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Studies of the habitability of the space shuttle orbiter are briefly summarized. Selected illustrations and descriptions are presented for: crew compartment, hygiene facilities, food system and galley, and storage systems.

  14. Report on orbital debris

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The success of space endeavors depends upon a space environment sufficiently free of debris to enable the safe and dependable operation of spacecraft. An environment overly cluttered with debris would threaten the ability to utilize space for a wide variety of scientific, technological, military, and commercial purposes. Man made space debris (orbital debris) differs from natural meteoroids because it remains in earth orbit during its lifetime and is not transient through the space around the Earth. The orbital debris environment is considered. The space environment is described along with sources of orbital debris. The current national space policy is examined, along with ways to minimize debris generation and ways to survive the debris environment. International efforts, legal issues and commercial regulations are also examined.

  15. PPPL Lorentz orbit code

    SciTech Connect

    Felt, J.; Barnes, C.W.; Chrien, R.E.; Cohen, S.A.; Heidbrink, W.W.; Manos, D.; Zweben, S. (Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (USA))

    1990-10-01

    A code that integrates the Lorentz force equation has been developed to trace a single charged particle's trajectory under the influence of toroidally symmetric magnetic fields found in tokamaks. This code is used primarily to design and estimate the efficiency of charged fusion product probes, which detect escaping energetic ions such as the 1 MeV tritons, 3 MeV protons, 15 MeV protons, and 3.5 MeV alphas created in TFTR. This interactive code has also been used as a teaching tool to illustrate classes of orbits such as trapped and passing, as well as subtle orbital motions, e.g., precession of banana orbits in tokamaks, or orbits in dipole magnetic field configuration. This paper describes the code as well as recent modifications which (1) include Shafranov shifts of the magnetic surfaces, (2) use more realistic current density profiles, and (3) allow modeling of the detector and limiters.

  16. Mars parking orbit selection

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Braun, Robert D.

    1990-01-01

    For a Mars mission, the selection of a parking orbit is greatly influenced by the precession caused by the oblateness of the planet. This affects the departure condition for earth return, and therefore, the mass required in LEO for a Mars mission. In this investigation, minimum LEO mass penalties were observed for parking orbits characterized by having near-equatorial inclinations, high eccentricities, and requiring a three-dimensional departure burn. However, because near-equatorial inclination orbits have poor planetary coverage characteristics, they are not desirable from a science viewpoint. To enhance these science requirements along with landing-site accessibility, a penalty in initial LEO mass is required. This study shows that this initial LEO mass penalty is reduced for orbits characterized with low to moderate eccentricities, nonequatorial inclinations, and a tangential periapsis arrival and departure burn.

  17. Indian Mars Orbiter Mission

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anil

    The Mars Orbiter Mission (MOM) is the first interplanetary mission of India launched by Indian Polar Satellite Launch Vehicle (PSLV-XL) on 5 November 2013. It departed from Earth's orbit on Dec. 1, 2013, on its 300-days journey to Mars. MOM will reach Mars on Sept. 24, 2014. The orbit of MOM around Mars is highly elliptical with periapsis ~370 km and apoapsis ~80000 km, inclination 151 degree, and orbital period 3.15 sols. The spacecraft mass is 1350 kg, with dry mass of 500 kg and science payload mass of 14 kg. The spacecraft carries five science payloads, namely: Methane Sensor for Mars (MSM), Mars Colour Camera (MCC), Lyman Alpha Photometer (LAP), Mars Exospheric Neutral Composition Analyzer (MENCA), TIR Imaging Spectrometer (TIS). This paper will present the details of the instruments, observation plan, and expected science.

  18. Altimetry, Orbits and Tides

    NASA Technical Reports Server (NTRS)

    Colombo, O. L.

    1984-01-01

    The nature of the orbit error and its effect on the sea surface heights calculated with satellite altimetry are explained. The elementary concepts of celestial mechanics required to follow a general discussion of the problem are included. Consideration of errors in the orbits of satellites with precisely repeating ground tracks (SEASAT, TOPEX, ERS-1, POSEIDON, amongst past and future altimeter satellites) are detailed. The theoretical conclusions are illustrated with the numerical results of computer simulations. The nature of the errors in this type of orbits is such that this error can be filtered out by using height differences along repeating (overlapping) passes. This makes them particularly valuable for the study and monitoring of changes in the sea surface, such as tides. Elements of tidal theory, showing how these principles can be combined with those pertinent to the orbit error to make direct maps of the tides using altimetry are presented.

  19. On the asteroid belt's orbital and size distribution

    NASA Astrophysics Data System (ADS)

    Gladman, Brett J.; Davis, Donald R.; Neese, Carol; Jedicke, Robert; Williams, Gareth; Kavelaars, J. J.; Petit, Jean-Marc; Scholl, Hans; Holman, Matthew; Warrington, Ben; Esquerdo, Gil; Tricarico, Pasquale

    2009-07-01

    For absolute magnitudes greater than the current completeness limit of H-magnitude ˜15 the main asteroid belt's size distribution is imperfectly known. We have acquired good-quality orbital and absolute H-magnitude determinations for a sample of small main-belt asteroids in order to study the orbital and size distribution beyond H=15, down to sub-kilometer sizes ( H>18). Based on six observing nights over a 11-night baseline we have detected, measured photometry for, and linked observations of 1087 asteroids which have one-week time baselines or more. The linkages allow the computation of full heliocentric orbits (as opposed to statistical distances determined by some past surveys). Judged by known asteroids in the field the typical uncertainty in the (a/e/i) orbital elements is less than 0.03 AU/0.03/0.5°. The distances to the objects are sufficiently well known that photometric uncertainties (of 0.3 magnitudes or better) dominate the error budget of their derived H-magnitudes. The detected asteroids range from H=12-22 and provide a set of objects down to sizes below 1 km in diameter. We find an on-sky surface density of 210 asteroids per square degree in the ecliptic with opposition magnitudes brighter than m=23, with the cumulative number of asteroids increasing by a factor of 10 0.27/mag from m=18 down to the m?23.5 limit of our survey. In terms of absolute H magnitudes, we find that beyond H=15 the belt exhibits a constant power-law slope with the number increasing proportional to 100.30H from H?15 to 18, after which incompleteness begins in the survey. Examining only the subset of detections inside 2.5 AU, we find weak evidence for a mildly shallower slope for H=15-19.5. We provide the information necessary such that anyone wishing to model the main asteroid belt can compare a detailed model to our detected sample.

  20. Mars Geoscience Orbiter and Lunar Geoscience Orbiter

    NASA Technical Reports Server (NTRS)

    Fuldner, W. V.; Kaskiewicz, P. F.

    1983-01-01

    The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The primary conclusion is that the basic AE/DE spacecraft can readily be applied to the LGO mission with relatively minor, low risk modifications. The MGO mission poses a somewhat more complex problem, primarily due to the overall maneuvering hydrazine budget and power requirements of the sensors and their desired duty cycle. These considerations dictate a modification (scaling up) of the structure to support mission requirements.

  1. Gravity and Orbits

    NSDL National Science Digital Library

    National Science Teachers Association (NSTA)

    2007-03-21

    The Gravity and Orbits SciPack explores concepts related to Earth's universal gravitation and how gravity affects the universe around us. The focus is on Standards and Benchmarks related to universal gravitation including variables that influence the amount of gravitational force and how gravity governs the motion of the solar system.In addition to comprehensive inquiry-based learning materials tied to Science Education Standards and Benchmarks, the SciPack includes the following additional components:? Pedagogical Implications section addressing common misconceptions, teaching resources and strand maps linking grade band appropriate content to standards. ? Access to one-on-one support via e-mail to content "Wizards".? Final Assessment which can be used to certify mastery of the concepts.Learning Outcomes:Gravity and Orbits: Universal Gravitation? Identify gravity as an attractive force associated with all objects, including less intuitive examples (such as soda cans and pencils).? Recognize some examples of phenomena that are the result of Earth's gravity and objects and structures in the universe in general.? Reject the idea that Earth's gravity is an effect of air pushing down toward the surface.? Recognize that gravitational force does not require air (or any other substance) as a medium to act.? Describe gravitational force as a mutual attraction, rather than as one object pulling on another.Gravity and Orbits: Gravitational Force? Identify variables that affect the strength of the gravitational force acting between any two objects.? Provide a quantitative description of the relationship between the mass of two object and the gravitational force between them.? Provide a qualitative description of the relationship between the mass of two objects and the gravitational force between them.? Provide a quantitative description of the relationship between distance and gravitational force. ? Provide a qualitative description of the inverse square relationship.? Recognize the effect of air resistance on object falling near Earth's surface, and thus be able to explain why two objects with different masses, at the same distance from Earth's surface, will have equal accelerations if air resistance is ignored. Gravity and Orbits: Orbits? Describe the conditions that would lead an object into orbital motion in terms of the effects of gravitational force.? Explain how an object orbits a planet in terms of trajectories and free fall.? Identify gravity as the force that keeps the planets in their orbits around the Sun and the moons in their orbits around the planets.

  2. GOCE Precise Science Orbits

    NASA Astrophysics Data System (ADS)

    Bock, Heike; Jäggi, Adrian; Meyer, Ulrich; Beutler, Gerhard; Heinze, Markus; Hugentobler, Urs

    GOCE (Gravity field and steady-state Ocean Circulation Explorer), as the first ESA (European Space Agency) Earth Explorer Core Mission, is dedicated for gravity field recovery of unprece-dented accuracy using data from the gradiometer, its primary science instrument. Data from the secondary instrument, the 12-channel dual-frequency GPS (Global Positioning System) receiver, is used for precise orbit determination of the satellite. These orbits are used to accu-rately geolocate the gradiometer observations and to provide complementary information for the long-wavelength part of the gravity field. A precise science orbit (PSO) product is provided by the GOCE High-Level Processing Facility (HPF) with a precision of about 2 cm and a 1-week latency. The reduced-dynamic and kinematic orbit determination strategies for the PSO product are presented together with results of about one year of data. The focus is on the improvement achieved by the use of empirically derived azimuth-and elevation-dependent variations of the phase center of the GOCE GPS antenna. The orbits are validated with satellite laser ranging (SLR) measurements.

  3. Sedna Orbit Comparisons

    NASA Technical Reports Server (NTRS)

    2004-01-01

    These four panels show the location of the newly discovered planet-like object, dubbed 'Sedna,' which lies in the farthest reaches of our solar system. Each panel, moving counterclockwise from the upper left, successively zooms out to place Sedna in context. The first panel shows the orbits of the inner planets, including Earth, and the asteroid belt that lies between Mars and Jupiter. In the second panel, Sedna is shown well outside the orbits of the outer planets and the more distant Kuiper Belt objects. Sedna's full orbit is illustrated in the third panel along with the object's current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. The final panel zooms out much farther, showing that even this large elliptical orbit falls inside what was previously thought to be the inner edge of the Oort cloud. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

  4. Orbits For Sixteen Binaries

    NASA Astrophysics Data System (ADS)

    Cvetkovic, Z.; Novakovic, B.

    2006-12-01

    In this paper orbits for 13 binaries are recalculated and presented. The reason is that recent observations show higher residuals than the corresponding ephemerides calculated by using the orbital elements given in the Sixth Catalog of Orbits of Visual Binary Stars. The binaries studied were: WDS 00182+7257 = A 803, WDS 00335+4006 = HO 3, WDS 00583+2124 = BU 302, WDS 01011+6022 = A 926, WDS 01014+1155 = BU 867, WDS 01112+4113 = A 655, WDS 01361-2954 + HJ 3447, WDS 02333+5219 = STT 42 AB, WDS 04362+0814 = A 1840 AB, WDS 08017-0836 = A 1580, WDS 08277-0425 = A 550, WDS 17471+1742 = STF 2215 and WDS 18025+4414 = BU 1127 Aa-B. In addition, for three binaries - WDS 01532+1526 = BU 260, WDS 02563+7253 =STF 312 AB and WDS 05003+3924 = STT 92 AB - the orbital elements are calculated for the first time. In this paper the authors present not only the orbital elements, but the masses, dynamical parallaxes, absolute magnitudes and ephemerides for the next five years, as well.

  5. Orbit maintenance for low altitude near-circular lunar orbits

    NASA Technical Reports Server (NTRS)

    Cook, Richard A.; Sweetser, Theodore H.

    1992-01-01

    The behavior of low altitude near-circular lunar orbits is a key design issue for some missions in the proposed Space Exploration Initiative. The lunar gravity field strongly perturbs low altitude orbits, so an effective orbit maintenance strategy is needed. This strategy must contend with the long term orbit evolution due to the zonal gravity field. Two possible orbit control scenarios are passive control using a frozen orbit and active orbit control using maneuvers. A maneuver strategy can be designed which optimizes the propellant required for long term orbit sustenance. The long term requirements dominate the total propellant required for orbit control. Additional propellant may be required to offset the impact of medium period gravity field effects. Careful selection of maneuver times and directions, however, can eliminate any medium period penalty.

  6. Elliptical vs Circular Orbit

    NSDL National Science Digital Library

    Bob Urschel

    Find the contrast between a highly exaggerated earth elliptical orbit and circular orbit depicted in .mov format. It should be mentioned to students that in reality the earth's elliptical orbit around the sun would hardly be noticeable if viewed from this distance. Taken alone, the video could unfortunately perpetuate the misconception that earth sun distance is responsible for the seasons. Still, the video is useful for pointing out that the earth's speed around the sun is not constant, with the earth moving fastest in January and slowest in July. This phenomenon helps explain why summer is longer in the Northern Hemisphere and for the analemma. The animation can be paused and rewound to emphasize important points.

  7. Spiral Orbit Tribometer

    NASA Technical Reports Server (NTRS)

    Pepper, Stephen V.; Jones, William R., Jr.; Kingsbury, Edward; Jansen, Mark J.

    2007-01-01

    The spiral orbit tribometer (SOT) bridges the gap between full-scale life testing and typically unrealistic accelerated life testing of ball-bearing lubricants in conjunction with bearing ball and race materials. The SOT operates under realistic conditions and quickly produces results, thereby providing information that can guide the selection of lubricant, ball, and race materials early in a design process. The SOT is based upon a simplified, retainerless thrust bearing comprising one ball between flat races (see figure). The SOT measures lubricant consumption and degradation rates and friction coefficients in boundary lubricated rolling and pivoting contacts. The ball is pressed between the lower and upper races with a controlled force and the lower plate is rotated. The combination of load and rotation causes the ball to move in a nearly circular orbit that is, more precisely, an opening spiral. The spiral s pitch is directly related to the friction coefficient. At the end of the orbit, the ball contacts the guide plate, restoring the orbit to its original radius. The orbit is repeatable throughout the entire test. A force transducer, mounted in-line with the guide plate, measures the force between the ball and the guide plate, which directly relates to the friction coefficient. The SOT, shown in the figure, can operate in under ultra-high vacuum (10(exp -9) Torr) or in a variety of gases at atmospheric pressure. The load force can be adjusted between 45 and 450 N. By varying the load force and ball diameter, mean Hertzian stresses between 0.5 and 5.0 GPa can be obtained. The ball s orbital speed range is between 1 and 100 rpm.

  8. Co-orbital Oligarchy

    E-print Network

    Benjamin F. Collins; Re'em Sari

    2009-01-13

    We present a systematic examination of the changes in semi-major axis caused by the mutual interactions of a group of massive bodies orbiting a central star in the presence of eccentricity dissipation. For parameters relevant to the oligarchic stage of planet formation, dynamical friction keeps the typical eccentricities small and prevents orbit crossing. Interactions at impact parameters greater than several Hill radii cause the protoplanets to repel each other; if the impact parameter is instead much less than the Hill radius, the protoplanets shift slightly in semi-major axis but remain otherwise unperturbed. If the orbits of two or more protoplanets are separated by less than a Hill radius, they are each pushed towards an equilibrium spacing between their neighbors and can exist as a stable co-orbital system. In the shear-dominated oligarchic phase of planet formation we show that the feeding zones contain several oligarchs instead of only one. Growth of the protoplanets in the oligarchic phase drives the disk to an equilibrium configuration that depends on the mass ratio of protoplanets to planetesimals, $\\Sigma/\\sigma$. Early in the oligarchic phase, when $\\Sigma/\\sigma$ is low, the spacing between rows of co-orbital oligarchs are about 5 Hill radii wide, rather than the 10 Hill radii cited in the literature. It is likely that at the end of oligarchy the average number of co-orbital oligarchs is greater than unity. In the outer solar system this raises the disk mass required to form the ice giants. In the inner solar system this lowers the mass of the final oligarchs and requires more giant impacts than previously estimated. This result provides additional evidence that Mars is not an untouched leftover from the oligarchic phase, but must be composed of several oligarchs assembled through giant impacts.

  9. Trajectories and Orbits

    NSDL National Science Digital Library

    Materials presented here outline some basic concepts associated with space flight. Users can read about orbits and the difference between an orbit and a trajectory, escape velocities for Earth and some planets, launch velocities and transit times for interplanetary flights, and the effects of time dilation for astronauts travelling at near-light speeds. This is part of the famous Rand corporation study that was commissioned by Congress in 1958 after the Soviet Union stunned the world by launching Sputnik, the world's first artificial satellite.

  10. Local orbitals by minimizing powers of the orbital variance

    NASA Astrophysics Data System (ADS)

    Jansík, Branislav; Høst, Stinne; Kristensen, Kasper; Jørgensen, Poul

    2011-05-01

    It is demonstrated that a set of local orthonormal Hartree-Fock (HF) molecular orbitals can be obtained for both the occupied and virtual orbital spaces by minimizing powers of the orbital variance using the trust-region algorithm. For a power exponent equal to one, the Boys localization function is obtained. For increasing power exponents, the penalty for delocalized orbitals is increased and smaller maximum orbital spreads are encountered. Calculations on superbenzene, C60, and a fragment of the titin protein show that for a power exponent equal to one, delocalized outlier orbitals may be encountered. These disappear when the exponent is larger than one. For a small penalty, the occupied orbitals are more local than the virtual ones. When the penalty is increased, the locality of the occupied and virtual orbitals becomes similar. In fact, when increasing the cardinal number for Dunning's correlation consistent basis sets, it is seen that for larger penalties, the virtual orbitals become more local than the occupied ones. We also show that the local virtual HF orbitals are significantly more local than the redundant projected atomic orbitals, which often have been used to span the virtual orbital space in local correlated wave function calculations. Our local molecular orbitals thus appear to be a good candidate for local correlation methods.

  11. Interplanetary orbit determination

    Microsoft Academic Search

    K. H. Rourke; N. Jerath; C. H. Acton; W. G. Breckenridge; J. K. Campbell; C. S. Christensen; A. J. Donegan; H. M. Koble; N. A. Mottinger; G. C. Rinker

    1979-01-01

    A general description of the Viking interplanetary orbit determination activity extending from launch to Mars encounter is given. The emphasis is on the technical fundamentals of the problem, basic strategies and data types used, quantitative results, and specific conclusions derived from the inflight experience. Special attention is given to the use of the spacecraft-based optical measurements and their first application

  12. Theory of Orbits

    Microsoft Academic Search

    Dino Boccaletti; Giuseppe Pucacco

    1996-01-01

    This textbook treats Celestial Mechanics as well as Stellar Dynamics from the common point of view of orbit theory making use of the concepts and techniques from modern geometric mechanics. It starts with elementary Newtonian Mechanics and ends with the dynamics of chaotic motions. The book is meant for students in astronomy and physics alike. Prerequisite is a physicist's knowledge

  13. Europa Orbiter Exploration Strategies

    NASA Technical Reports Server (NTRS)

    Johnson, T. V.

    2001-01-01

    The Europa Orbiter mission is planned as the next stage of Europa exploration. Its primary goals are to search for definitive evidence of a subsurface ocean, to characterize the ice crust and ice/water interface, and to prepare for future surface/sub-surface missions. Additional information is contained in the original extended abstract.

  14. Orbital Forces: Teacher Page

    NSDL National Science Digital Library

    This activity demonstates orbital motions and forces using a tennis ball swung by a ribbon (this activity should be done outside). The Teacher Page contains background information, tennis ball preparation instructions, and wrap up information. This activity is part of Exploring Planets in the Classroom's Planetary Properties series.

  15. Orbital Forces: Student Page

    NSDL National Science Digital Library

    This activity teaches students about orbital motions and forces using a tennis ball swung by a ribbon. Students answer the question "What happens when you let the ball go?" Background information, activity procedures, and key words are provided. This activity is part of Exploring Planets in the Classroom's Planetary Properties series.

  16. ICESat Precision Orbit Determination

    Microsoft Academic Search

    H. Rim; S. Yoon; C. E. Webb; Y. Kim; B. E. Schutz

    2003-01-01

    Following the successful launch of the Ice, Cloud and land Elevation Satellite (ICESat) on January 13, 2003, 00:45 UTC, the GPS receiver on ICESat was turned on successfully on Jan. 17, 2003. High quality GPS data were collected since then to support Precision Orbit Determination (POD) activities. ICESat carries Geoscience Laser Altimeter System (GLAS) to measure ice-sheet topography and associated

  17. Lunar Orbit Anomaly

    NASA Astrophysics Data System (ADS)

    Riofrio, L.

    2012-12-01

    Independent experiments show a large anomaly in measurements of lunar orbital evolution, with applications to cosmology and the speed of light. The Moon has long been known to be slowly drifting farther from Earth due to tidal forces. The Lunar Laser Ranging Experiment (LLRE) indicates the Moon's semimajor axis increasing at 3.82 ± .07 cm/yr, anomalously high. If the Moon were today gaining angular momentum at this rate, it would have coincided with Earth less than 2 Gyr ago. Study of tidal rhythmites indicates a rate of 2.9 ± 0.6 cm/yr. Historical eclipse observations independently measure a recession rate of 2.82 ± .08 cm/yr. Detailed numerical simulation of lunar orbital evolution predicts 2.91 cm/yr. LLRE differs from three independent experiments by over12 sigma. A cosmology where speed of light c is related to time t by GM=tc^3 has been suggested to predict the redshifts of Type Ia supernovae, and a 4.507034% proportion of baryonic matter. If c were changing in the amount predicted, lunar orbital distance would appear to increase by an additional 0.935 cm/yr. An anomaly in the lunar orbit may be precisely calculated, shedding light on puzzles of 'dark energy'. In Planck units this cosmology may be summarized as M=R=t.Lunar Recession Rate;

  18. Measuring the Moon's Orbit.

    ERIC Educational Resources Information Center

    Sarton, E. Jay

    1980-01-01

    Described is a project which measured the parameters of the moon's orbit and the moon's size with various equipment, photographs, and calculations. The goals for this project included: completion within a 6-8 week period, reliance on existing equipment and data obtained, and provision for hands-on experience to advanced high school students.…

  19. CO-ORBITAL OLIGARCHY

    SciTech Connect

    Collins, Benjamin F.; Sari, Re'em [California Institute of Technology, MC 130-33, Pasadena, CA 91125 (United States)], E-mail: bfc@tapir.caltech.edu

    2009-04-15

    We present a systematic examination of the changes in semimajor axis of a protoplanet as it interacts with other protoplanets in the presence of eccentricity dissipation. For parameters relevant to the oligarchic stage of planet formation, dynamical friction keeps the typical eccentricities small and prevents orbit crossing. Interactions at impact parameters greater than several Hill radii cause the protoplanets to repel each other; if the impact parameter is instead much less than the Hill radius, the protoplanets shift slightly in semimajor axis but remain otherwise unperturbed. If the orbits of two or more protoplanets are separated by less than a Hill radius, they are each pushed toward an equilibrium spacing between their neighbors and can exist as a stable co-orbital system. In the shear-dominated oligarchic phase of planet formation, we show that the feeding zones contain several oligarchs instead of only one. Growth of the protoplanets in the oligarchic phase drives the disk to an equilibrium configuration that depends on the mass ratio of protoplanets to planetesimals, {sigma}/{sigma}. Early in the oligarchic phase, when {sigma}/{sigma} is low, the spacing between rows of co-orbital oligarchs are about 5 Hill radii wide, rather than the 10 Hill radii cited in the literature. It is likely that at the end of oligarchy, the average number of co-orbital oligarchs is greater than unity. In the outer solar system, this raises the disk mass required to form the ice giants. In the inner solar system, this lowers the mass of the final oligarchs and requires more giant impacts than previously estimated. This result provides additional evidence that Mars is not an untouched leftover from the oligarchic phase, but must be composed of several oligarchs assembled through giant impacts.

  20. Extrasolar Planetary Imaging Coronagraph: Visible Nulling Coronagraph Testbed Results

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.

    2008-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime ( 5 year goal) and will revisit planets at least three times at intervals of 9 months. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables high order starlight suppression in broadband light. To demonstrate the VNC approach and advance it's technology readiness the NASA Goddard Space Flight Center and Lockheed-Martin have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed,

  1. Visible Nulling Coronagraph Testbed Results

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Melnick, Gary; Tolls, Volker; Woodruff, Robert; Vasudevan, Gopal; Rizzo, Maxime; Thompson, Patrick

    2009-01-01

    The Extrasolar Planetary Imaging Coronagraph (EPIC) is a NASA Astrophysics Strategic Mission Concept study and a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC would provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 5-year mission lifetime. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables starlight suppression in broadband light from 480-960 nm. To demonstrate the VNC approach and advance it's technology readiness we have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed.

  2. Forbidden tangential orbit transfers between intersecting Keplerian orbits

    NASA Technical Reports Server (NTRS)

    Burns, Rowland E.

    1990-01-01

    The classical problem of tangential impulse transfer between coplanar Keplerian orbits is addressed. A completely analytic solution which does not rely on sequential calculation is obtained and this solution is used to demonstrate that certain initially chosen angles can produce singularities in the parameters of the transfer orbit. A necessary and sufficient condition for such singularities is that the initial and final orbits intersect.

  3. Lunar Exploration Orbiter

    NASA Astrophysics Data System (ADS)

    Henselowsky, Carsten; Jaumann, Ralf; Kummer, Uwe; Claasen, Friedhelm

    Phase 0 investigations for the German Lunar Exploration Orbiter (LEO) mission were carried out during 2007 leading to a sophisticated mission concept currently in phase A to be further detailed. Following an announcement of opportunity, also in 2007, the German Space Agency (DLR) received several proposals for the instrumentation of the LEO mission from the national science community. A board of peers recommended 12 instruments for a further consideration in phase A. Overall premise for the accomplishment of LEO is that the mission will provide high quality scientific output in the fields of geology, geochemistry and geophysics and add value in the context of already operational and foreseeable upcoming lunar missions. Composed of three satellites, a main orbiter and a pair of sub-satellites, the Lunar Exploration Orbiter will investigate the moon in all its facets, including its interior constitution and development by gravity field analysis, its surface in a multifold of aspects, ranging from topography to mineralogy, as well as its direct surrounding in aspects as radiation and dust. To accomplish this challenging mission objective, with respect to the envisaged high spatial and spectral resolution of the global surface mapping and the accuracy of the determination of the gravity field, the mission concept stipulates a mean altitude of 50 km. Due to the request for global coverage, low altitude and the quantity of instruments LEO is designed for a nominal operational lifetime of four years. Necessary mission lifetime and altitude combined with the capricious lunar gravity field yields a less propellant demanding frozen orbit with an inclination of 85° which is envisaged for the first part of the operational period. The LEO main orbiter will change its inclination to polar orbit after three years of operation to complete global coverage during the last nominal year of operation. The two sub-satellites will remain in the stable, initial 50 km orbit. Remaining propellant will be used to deal with uncertainties according to the considered lunar frozen orbits or for an extension of the nominal lifetime and/or scenario. The LEO main orbiter will carry the mapping payloads that will provide global coverage of the moon surface and the environmental examination instruments: Three imaging spectrometers covering a wide spectral range from 200 nm up to 14 µm, will provide data for geochemical investigations, a camera for highest resolution stereo imaging will establish a three-dimensional topographic map and a specialized camera for event detection will identify lunar transient events, a microwave and a radar instrument will investigate the lunar subsurface, environmental instruments shall measure the lunar radiation and particle (dust) environment. The two - almost identical - subsatellites together form an instrument to determine the lunar gravity field with unprecedented high accuracy, by conducting range and range-rate measurements. Moreover each sub-satellite is determined to carry also a magnetometer and a sensor measuring the pressure of radiation to assist gravity field measurements. As mentioned above, first and foremost LEO is a scientific driven mission. Over and above the scientific ambition LEO shall be Germany's contribution to future lunar exploration in an international context by providing a global scientific roadmap of the Moon with highest precision. LEO is planed to be launched in 2012 timeframe.

  4. Analysis of orbital heat transfer

    NASA Technical Reports Server (NTRS)

    Buna, T.

    1974-01-01

    Graphical representation of orbital heat balance in form of polar diagrams is obtained from integral expressions of orbital heat transfer whereby quantities of heat are represented as areas swept by ""thermal radii.''

  5. Orbital metastasis from cutaneous melanoma.

    PubMed

    Bond, J B; Wesley, R E; Reynolds, V H; Elliott, J H; Glick, A D

    1986-11-01

    Although orbital extension from ocular melanoma occurs frequently in advanced cases, orbital metastasis from cutaneous melanoma has been reported but eight times previously. We have reported two such cases. One of the patients had three previous primary melanomas; the other had metastasis to the cauda equina. Both patients died when orbital involvement developed years after the initial lesions. Ours are the first cases to include CT and MRI findings in metastatic orbital melanoma. PMID:3775474

  6. Martian satellite orbits and ephemerides

    NASA Astrophysics Data System (ADS)

    Jacobson, R. A.; Lainey, V.

    2014-11-01

    We discuss the general characteristics of the orbits of the Martian satellites, Phobos and Deimos. We provide a concise review of the various descriptions of the orbits by both analytical theories and direct numerical integrations of their equations of motion. After summarizing the observational data used to determine the orbits, we discuss the results of our latest orbits obtained from a least squares fit to the data.

  7. Plotting Orbital Trajectories For Maneuvers

    NASA Technical Reports Server (NTRS)

    Brody, Adam R.

    1991-01-01

    Interactive Orbital Trajectory Planning Tool (EIVAN) computer program is forward-looking interactive orbit-trajectory-plotting software tool for use with proximity operations (operations occurring within 1-km sphere of space station) and other maneuvers. Developed to plot resulting trajectories, to provide better comprehension of effects of orbital mechanics, and to help user develop heuristics for planning missions on orbit. Program runs with Microsoft's Excel for execution on MacIntosh computer running MacIntosh OS.

  8. Circular-Orbit Maintenance Strategies for Primitive Body Orbiters

    NASA Technical Reports Server (NTRS)

    Wallace, Mark S.; Broschart, Stephen

    2013-01-01

    For missions to smaller primitive bodies, solar radiation pressure (SRP) is a significant perturbation to Keplerian dynamics. For most orbits, SRP drives large oscillations in orbit eccentricity, which leads to large perturbations from the irregular gravity field at periapsis. Ultimately, chaotic motion results that often escapes or impacts that body. This paper presents an orbit maintenance strategy to keep the orbit eccentricity small, thus avoiding the destabilizing secondary interaction with the gravity field. An estimate of the frequency and magnitude of the required maneuvers as a function of the orbit and body parameters is derived from the analytic perturbation equations.

  9. An Orbit Plan toward AKATSUKI Venus Reencounter and Orbit Injection

    NASA Technical Reports Server (NTRS)

    Kawakatsu, Yasuhiro; Campagnola, Stefano; Hirose, Chikako; Ishii, Nobuaki

    2012-01-01

    On December 7, 2010, AKATSUKI, the Japanese Venus explorer reached its destination and tried to inject itself into Venus orbit. However, due to a malfunction of the propulsion system, the maneuver was interrupted and AKATSUKI again escaped out from the Venus into an interplanetary orbit. Telemetry data from AKATSUKI suggests the possibility to perform orbit maneuvers to reencounter the Venus and retry Venus orbit injection. Reported in this paper is an orbit plan investigated under this situation. The latest results reflecting the maneuvers conducted in the autumn 2011 is introduced as well.

  10. Lymphoproliferative Disease of the Orbit.

    PubMed

    Li, Emmy Y; Yuen, Hunter K; Cheuk, Wah

    2015-01-01

    Lymphoproliferative diseases of the orbit account for majority of orbital tumors. The pathologies range from reactive lymphoid hyperplasia to specific IgG4-related inflammation to malignant lymphomas. This review summarizes current concepts regarding pathology, clinical presentation, diagnosis, staging, and treatment strategies of major orbital lymphoproliferative diseases based on updated and relevant bibliography. PMID:26065355

  11. Orbit Mechanics About Planetary Satellites

    Microsoft Academic Search

    M. E. Paskowitzyand; D. J. Scheeresz

    This paper explores orbit mechanics in the Hill 3-body problem, concentrating on spacecraft motion about Jupiter's moon Europa. Orbits about Europa are of particular interest due to the proposed NASA Jupiter Icy Moons Orbiter Mission (JIMO). Using an averaging approach with first order corrections, we develop an approximate theory of motion valid over a wide range of initial conditions. Using

  12. Orbiter OMS and RCS technology

    NASA Technical Reports Server (NTRS)

    Boudreaux, R. A.

    1982-01-01

    Orbiter Orbital Maneuver Subsystem (OMS) and Reaction Control Subsystem (RCS) tankage has proved to be highly successful in shuttle flights on-orbit propellant transfer tests were done. Tank qualification tests along with flight demonstrations were carried out future uses of storable propellants are cited.

  13. Mercury orbiter transport study

    NASA Technical Reports Server (NTRS)

    Friedlander, A. L.; Feingold, H.

    1977-01-01

    A data base and comparative performance analyses of alternative flight mode options for delivering a range of payload masses to Mercury orbit are provided. Launch opportunities over the period 1980-2000 are considered. Extensive data trades are developed for the ballistic flight mode option utilizing one or more swingbys of Venus. Advanced transport options studied include solar electric propulsion and solar sailing. Results show the significant performance tradeoffs among such key parameters as trip time, payload mass, propulsion system mass, orbit size, launch year sensitivity and relative cost-effectiveness. Handbook-type presentation formats, particularly in the case of ballistic mode data, provide planetary program planners with an easily used source of reference information essential in the preliminary steps of mission selection and planning.

  14. Three orbital transfer vehicles

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Aerospace engineering students at the Virginia Polytechnic Institute and State University undertook three design projects under the sponsorship of the NASA/USRA Advanced Space Design Program. All three projects addressed cargo and/or crew transportation between low Earth orbit and geosynchronous Earth orbit. Project SPARC presents a preliminary design of a fully reusable, chemically powered aeroassisted vehicle for a transfer of a crew of five and a 6000 to 20000 pound payload. The ASTV project outlines a chemically powered aeroassisted configuration that uses disposable tanks and a relatively small aerobrake to realize propellant savings. The third project, LOCOST, involves a reusable, hybrid laser/chemical vehicle designed for large cargo (up to 88,200 pounds) transportation.

  15. Orbital rhabdomyosarcomas: A review

    PubMed Central

    Jurdy, Lama; Merks, Johanus H.M.; Pieters, Bradly R.; Mourits, Maarten P.; Kloos, Roel J.H.M.; Strackee, Simone D.; Saeed, Peerooz

    2013-01-01

    Rhabdomyosarcoma (RMS) is a highly malignant tumor and is one of the few life-threatening diseases that present first to the ophthalmologist. It is the most common soft-tissue sarcoma of the head and neck in childhood with 10% of all cases occurring in the orbit. RMS has been reported from birth to the seventh decade, with the majority of cases presenting in early childhood. Survival has changed drastically over the years, from 30% in the 1960’s to 90% presently, with the advent of new diagnostic and therapeutic modalities. The purpose of this review is to provide a general overview of primary orbital RMS derived from a literature search of material published over the last 10 years, as well as to present two representative cases of patients that have been managed at our institute. PMID:24227982

  16. Generation of NEP heliocentric trajectory data

    NASA Technical Reports Server (NTRS)

    Horsewood, J. L.; Brice, K. B.

    1972-01-01

    A study, designed to generate representative nuclear electric propulsion data for rendezvous missions to the comet Encke using the variational calculus program HILTOP, is presented. Other purposes of the study include a comparison of the HILTOP data with equivalent data generated with QUICKTOP program and to propose approaches for storing and subsequently accessing the optimum trajectory and performance data in the QUICKLY program.

  17. The Orbit of Charon

    Microsoft Academic Search

    David J. Tholen; Mark W. Buie

    1997-01-01

    The orbit of Charon has been determined from 60 images of the Pluto–Charon system acquired with the Hubble Space Telescope Wide Field and Planetary Camera between 1992 May 21 and 1993 August 18. The semimajor axis was found to be 19,636 ± 8 km, in good agreement with an older determination upon which mutual-event-based radius computations have relied, but significantly

  18. Orbital Debris Modeling

    NASA Technical Reports Server (NTRS)

    Liou, J. C.

    2012-01-01

    Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)

  19. Spectrophotovoltaic orbital power generation

    NASA Technical Reports Server (NTRS)

    Onffroy, J. R.

    1980-01-01

    The feasibilty of a spectrophotovoltaic orbital power generation system that optically concentrates solar energy is demonstrated. A dichroic beam-splitting mirror is used to divide the solar spectrum into two wavebands. Absorption of these wavebands by GaAs and Si solar cell arrays with matched energy bandgaps increases the cell efficiency while decreasing the amount of heat that must be rejected. The projected cost per peak watt if this system is $2.50/W sub p.

  20. Small Mercury Relativity Orbiter

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  1. Earth Co-orbital Objects

    NASA Astrophysics Data System (ADS)

    Wiegert, P.; Connors, M.; Chodas, P.; Veillet, C.; Mikkola, S.; Innanen, K.

    2002-12-01

    The recent discovery of asteroid 2002 AA29 by the LINEAR survey and the realization of its co-orbital relationship with Earth lead us to consider the characteristics of Earth Co-orbital Objects (ECOs) in general. An object with semimajor axis between 0.99 and 1.01 AU is in 1:1 resonance with the Earth. To be co-orbital in the sense of moving along the Earth's orbit, an object must further have its other orbital parameters similar to those of the Earth. Clarification is needed as to what range of orbital parameters can be regarded as similar enough to permit classification as an ECO. ECOs would be expected to librate on tadpole or horseshoe orbits, be relatively easy to access with spacecraft, and to sometimes exhibit quasisatellite behavior. 2002 AA29 is on a horseshoe orbit and was discovered in a general asteroid survey while near Earth at one end of the horseshoe orbit. Searches for Earth Trojan asteroids, which would be members of the ECO class on tadpole orbits near a triangular Lagrange Point, have not yet been successful. While 2002 AA29 has an orbit even less eccentric than Earth's, it has an inclination of about 10 degrees. 2000 PH5 and 2001 GO2 are on horseshoe orbits and interact gravitationally with Earth to 'bounce' when they approach the Earth from either side. With eccentricities of .23 and .17 respectively, they do not have decidedly Earth-like orbits despite inclinations less that 5 degrees. When in quasi-satellite mode, a body exhibits a looping motion relative to Earth in some ways resembling a satellite orbit. Several resonant bodies including 3753 Cruithne exhibit this behavior at times, but ECOs remain close to Earth while doing it. We suggest that directed searches be used to discover ECOs and characterize this class of objects. Orbital simulations suggest the best target spaces, which are only partially covered by present general searches.

  2. Weather Satellite and Orbits

    NSDL National Science Digital Library

    In this interactive, online module, students learn about satellite orbits (geostationary and polar), remote-sensing satellite instruments (radiometers and sounders), satellite images, and the math and physics behind satellite technology. The module is part of an online course for grades 7-12 in satellite meteorology, which includes 10 interactive modules. The site also includes lesson plans developed by teachers and links to related resources. Each module is designed to serve as a stand-alone lesson, however, a sequential approach is recommended. Designed to challenge students through the end of 12th grade, middle school teachers and students may choose to skim or skip a few sections.

  3. The Earth's Orbit

    NSDL National Science Digital Library

    2007-12-12

    These eleven activities relate to the results of the motion and position of the Earth in its orbit, investigating both the causes and the effects of changing seasons. It starts simply by trying to quantify the observation that it is colder in the winter and ends by measuring the tilt of the Earth. This is chapter two of the online book Eyes on the Sky, Feet on the Ground, containing explorations into astronomy as a classroom tool for learning how to theorize, experiment, and analyze data. The activities are fully illustrated and contain detailed, step-by-step instructions as well as suggested discussion topics.

  4. Triple Difference Approach to Low Earth Orbiter Precision Orbit Determination

    Microsoft Academic Search

    Jay-Hyoun Kwon; Dorota A. Grejner-Brzezinska; Jae-Hong Yom; Lee-Dong Cheon

    2003-01-01

    A precise kinematic orbit determination (P-KOD) procedure for Low Earth Orbiter(LEO) using the GPS ion-free triple differenced carrier phases is presented. Because the triple differenced observables provide only relative information, the first epoch's positions of the orbit should be held fixed. Then, both forward and backward filtering was executed to mitigate the effect of biases of the first epoch's position.

  5. Telescope with 100 square degree field-of-view for NASA's Kepler mission

    NASA Astrophysics Data System (ADS)

    Ebbets, Dennis; Stewart, Chris; Spuhler, Peter; Atcheson, Paul; Cleve, Jeffrey Van; Bryson, Stephen; Clarkson, Andrew; Barentine, John

    2013-09-01

    Kepler is NASA's first space mission dedicated to the study of exoplanets. The primary scientific goal is statistical-to estimate the frequency of planetary systems associated with sun-like stars, especially the detection of earth-size planets in the habitable zones. Kepler was launched into an Earth-trailing heliocentric "drift-away" orbit (period=372 days) in March 2009. The instrument detects the faint photometric signals of transits of planets across the stellar disks of those systems with orbital planes fortuitously oriented in our line of sight. Since the probability of such alignments is small, Kepler must observe a large number of stars. In fact, Kepler is monitoring approximately 150,000 stars with a 30-min cadence. The scientific goals led to the choice of a classical Schmidt telescope, and requirements on field-of-view, throughput, spectral bandpass, image quality, scattered light, thermal and opto-mechanical stability, and in-flight adjustment authority. We review the measurement requirements, telescope design, prelaunch integration, alignment, and test program, and we describe the in-flight commissioning that optimized the performance. The stability of the flight system has enabled increasing recognition of small effects and sophistication in data processing algorithms. Astrophysical noise arising from intrinsic stellar variability is now the dominant term in the photometric error budget.

  6. Structure of the zodiacal emission by Spitzer archive data

    NASA Astrophysics Data System (ADS)

    Verebelyi, E.; Kiss, C.; Balog, Z.; Stansberry, J.

    2014-07-01

    Dust in the interplanetary dust cloud not just reflects the sunlight (known as zodiacal light) but also has its own thermal emission. At the heliocentric distance of the Earth, the peak of this emission (with particle size ˜ 100 ? m) is close to 20 ? m. In this study, we used the data of four programs completed with the MIPS camera of the Spitzer Space Telescope at 24 ? m to probe the large-scale brightness distribution as well as the small-scale (sub-arcmin) structure of the zodiacal cloud. The four programs were: - The Production of Zodiacal Dust by Asteroids and Comets (ID: 2317) - High Latitude Dust Bands in the Main Asteroid Belt: Fingerprints of Recent Breakup Events (ID: 20539) - A New Source of Interplanetary Dust: Type II Dust Trails (ID: 30545) - First Look Survey - Ecliptic Plane Component (ID: 98) We take into account that, when the Spitzer Space Telescope carried out the measurements, it was orbiting the Sun at an Earth-trailing orbit and looking at different parts of the zodiacal cloud, in many cases looking through the same parts of the cloud from different locations. This gives us the chance to investigate the 3D distribution of zodiacal dust in addition to large- and small-scale structure of the cloud.

  7. Space Station: Orbiter berthing

    NASA Astrophysics Data System (ADS)

    Mapar, J.; Lin, Y. C.; Kilby, M.

    1992-01-01

    The berthing/docking maneuver is important for the construction and assembly of the Space Station Freedom (SSF). Berthing has a direct effect on the SSF assembly build up and SSF/Orbiter operations. The dynamics associated with the berthing activities potentially large impacts on the elements ans systems (both the Orbiter and SSF) throughout the assembly sequence. These dynamics will play a major role in the development of operational requirements that need to be identified and validated in order to assure total safety and maneuver execution during the SSF construction. The berthing/docking task will consider those assembly flights where the SSF has the control authority for the combined stack (currently MB-5) and beyond. The purpose of this task is to analyze the effects of berthing dynamics and their impacts on the maneuver and operational requirements. The task objectives are the following: (1) to develop the necessary analytical tool(s) and skills that will enable the verification and certification of berthing/docking for each assembly flight; (2) to perform detailed analyses of the berthing/docking maneuvers during the SSF assembly buildup in order to verify the viability of such maneuvers; and (3) to develop the operational requirements that affect such maneuvers and establish the operational boundaries and envelops for berthing/docking during assembly and mature operations. Various topics are presented in viewgraph form and include the following: analysis tools and capabilities; analysis results; and ongoing work.

  8. Physical Properties of Fireball-Producing Earth-Impacting Meteoroids and Orbit Determination through Shadow Calibration of the Buzzard Coulee Meteorite Fall

    NASA Astrophysics Data System (ADS)

    Milley, Ellen Palesa

    The physical properties of the meteoroid population were investigated through combining data from a number of fireball camera networks. PE values, as a measure of meteoroid strength, were calculated and linked with other observational criteria (Tisserand parameter, meteor shower identification). The historic divisions for fireball types based on the PE criterion were not observed in the large data set, but a correlation with source region was recognized. Meteor showers demonstrated different amounts of variation in PE values potentially related to the materials found in each parent comet. The trajectory and pre-fall orbit for the Buzzard Coulee meteoroid were determined through the calibration of shadows cast by the fireball. The method of using shadows to triangulate a trajectory was developed and evaluated. The best fit trajectory was coupled with an initial velocity of 18.0 km/s to compute the heliocentric orbit. Buzzard Coulee fell from a modestly inclined near-Earth Apollo orbit. It is the 12th fallen meteorite to be associated with an orbit.

  9. Photometry of 2006 RH{120}: an asteroid temporary captured into a geocentric orbit

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, T.; Kryszczy?ska, A.; Poli?ska, M.; Buckley, D. A. H.; O'Donoghue, D.; Charles, P. A.; Crause, L.; Crawford, S.; Hashimoto, Y.; Kniazev, A.; Loaring, N.; Romero Colmenero, E.; Sefako, R.; Still, M.; Vaisanen, P.

    2009-03-01

    Aims: From July 2006 to July 2007 a very small asteroid orbited the Earth within its Hill sphere. We used this opportunity to study its rotation and estimate its diameter and shape. Methods: Due to its faintness, 2006 RH{120} was observed photometrically with the new 10-m SALT telescope at the SAAO (South Africa). We obtained data on four nights: 11, 15, 16, and 17 March 2007 when the solar phase angle remained almost constant at 74°. The observations lasted about an hour each night and the object was exposed for 7-10 s through the “clear” filter. Results: From the lightcurves obtained on three nights we derived two solutions for a synodical period of rotation: P1 = 1.375 ± 0.001 min and P2 = 2.750 ± 0.002 min. The available data are not sufficient to choose between them. The absolute magnitude of the object was found to be H = 29.9 ± 0.3 mag (with the assumed slope parameter G = 0.25) and its effective diameter D = 2-7 m, depending on the geometric albedo pV (with the most typical near-Earth asteroids albedo pV = 0.18 its diameter would be D = 3.3 ± 0.4 m). The body has an elongated shape with the a/b ratio greater than 1.4. It probably originates in low-eccentricity Amor or Apollo orbits. There is still a possibility, which needs further investigation, that it is a typical near-Earth asteroid that survived the aerobraking in the Earth's atmosphere and returned to a heliocentric orbit similar to that of the Earth. Based on observations made with the Southern African Large Telescope (SALT).

  10. Ancient schwannoma of the orbit.

    PubMed

    Pecorella, I; Toth, J; Lukats, O

    2012-08-01

    Schwannoma, also referred to as neurilemmoma or peripheral neurinoma, is an unusual orbital benign tumour that may pose diagnostic challenges. Awareness of the clinical features that may be associated with the tumour and prompt surgical excision with histopathologic examination enable correct diagnosis. The authors describe a progressively increasing inferolateral orbital mass in a 32-year-old patient that was demonstrated to be an orbital ancient schwannoma. PMID:23316621

  11. Orbital myositis: Diagnosis and management

    Microsoft Academic Search

    Roberta M. S. Costa; Oana M. Dumitrascu; Lynn K. Gordon

    2009-01-01

    Orbital myositis is an inflammatory process that primarily involves the extraocular muscles and most commonly affects young\\u000a adults in the third decade of life, with a female predilection. Clinical characteristics of orbital myositis include orbital\\u000a and periorbital pain, ocular movement impairment, diplopia, proptosis, swollen eyelids, and conjunctival hyperemia. The most\\u000a common presentation is acute and unilateral, which initially responds to

  12. Orbits in Space: Lagrangian points

    NSDL National Science Digital Library

    Stern, David P. (David Peter), 1931-

    Authored and curated by David P. Stern, these pages explore orbits and the "Lagrangian points", where objects will orbit the sun with the same period as the earth. This has applications for solar monitoring spacecraft. The three sections derive the equilibrium properties of Lagrangian points: the calculations only involve algebra and trig, but are rather lengthy. This is a nice introduction to these rather complex theories of orbits in space. Translations to French and (in part) Spanish are also provided.

  13. OSO-6 Orbiting Solar Observatory

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The description, development history, test history, and orbital performance analysis of the OSO-6 Orbiting Solar Observatory are presented. The OSO-6 Orbiting Solar Observatory was the sixth flight model of a series of scientific spacecraft designed to provide a stable platform for experiments engaged in the collection of solar and celestial radiation data. The design objective was 180 days of orbital operation. The OSO-6 has telemetered an enormous amount of very useful experiment and housekeeping data to GSFC ground stations. Observatory operation during the two-year reporting period was very successful except for some experiment instrument problems.

  14. Orbital State Uncertainty Realism

    NASA Astrophysics Data System (ADS)

    Horwood, J.; Poore, A. B.

    2012-09-01

    Fundamental to the success of the space situational awareness (SSA) mission is the rigorous inclusion of uncertainty in the space surveillance network. The *proper characterization of uncertainty* in the orbital state of a space object is a common requirement to many SSA functions including tracking and data association, resolution of uncorrelated tracks (UCTs), conjunction analysis and probability of collision, sensor resource management, and anomaly detection. While tracking environments, such as air and missile defense, make extensive use of Gaussian and local linearity assumptions within algorithms for uncertainty management, space surveillance is inherently different due to long time gaps between updates, high misdetection rates, nonlinear and non-conservative dynamics, and non-Gaussian phenomena. The latter implies that "covariance realism" is not always sufficient. SSA also requires "uncertainty realism"; the proper characterization of both the state and covariance and all non-zero higher-order cumulants. In other words, a proper characterization of a space object's full state *probability density function (PDF)* is required. In order to provide a more statistically rigorous treatment of uncertainty in the space surveillance tracking environment and to better support the aforementioned SSA functions, a new class of multivariate PDFs are formulated which more accurately characterize the uncertainty of a space object's state or orbit. The new distribution contains a parameter set controlling the higher-order cumulants which gives the level sets a distinctive "banana" or "boomerang" shape and degenerates to a Gaussian in a suitable limit. Using the new class of PDFs within the general Bayesian nonlinear filter, the resulting filter prediction step (i.e., uncertainty propagation) is shown to have the *same computational cost as the traditional unscented Kalman filter* with the former able to maintain a proper characterization of the uncertainty for up to *ten times as long* as the latter. The filter correction step also furnishes a statistically rigorous *prediction error* which appears in the likelihood ratios for scoring the association of one report or observation to another. Thus, the new filter can be used to support multi-target tracking within a general multiple hypothesis tracking framework. Additionally, the new distribution admits a distance metric which extends the classical Mahalanobis distance (chi^2 statistic). This metric provides a test for statistical significance and facilitates single-frame data association methods with the potential to easily extend the covariance-based track association algorithm of Hill, Sabol, and Alfriend. The filtering, data fusion, and association methods using the new class of orbital state PDFs are shown to be mathematically tractable and operationally viable.

  15. A survey of orbits of co-orbitals of Mars

    NASA Astrophysics Data System (ADS)

    Connors, Martin; Stacey, Greg; Brasser, Ramon; Wiegert, Paul

    2005-05-01

    Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF 31, were discovered, librating about the L 5 Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ 7, to be a Trojan, associated with the L 4 Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND 43) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW 15 and 2000 TG 2, within the resonant region capable of undergoing what we designate "circulation transition", in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion.

  16. TOPEX orbital radiation study

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; Barth, J. M.

    1984-01-01

    The space radiation environment of the TOPEX spacecraft is investigated. A single trajectory was considered. The external (surface incident) charged particle radiation, predicted for the satellite, is determined by orbital flux integration for the specified trajectory. The latest standard models of the environment are used in the calculations. The evaluation is performed for solar maximum conditions. The spacecraft exposure to cosmic rays of galactic origin is evaluated over its flight path through the magnetosphere in terms of geomagnetic shielding effects, both for surface incident heavy ions and for particles emerging behind different material thickness. Limited shielding and dose evaluations are performed for simple infinite slab and spherical geometries. Results, given in graphical and tabular form, are analyzed, explained, and discussed. Conclusions are presented and commented on.

  17. Orbital magnetic ratchet effect

    NASA Astrophysics Data System (ADS)

    Budkin, G. V.; Golub, L. E.

    2014-09-01

    Magnetic ratchets—two-dimensional systems with superimposed noncentrosymmetric ferromagnetic gratings—are considered theoretically. It is demonstrated that excitation by radiation results in a directed motion of two-dimensional carriers due to the pure orbital effect of the periodic magnetic field. Magnetic ratchets based on various two-dimensional systems such as topological insulators, graphene, and semiconductor heterostructures are investigated. The mechanisms of the electric current generation caused by both radiation-induced heating of carriers and by acceleration in the radiation electric field in the presence of a space-oscillating Lorentz force are studied in detail. The electric currents sensitive to the linear polarization plane orientation as well as to the radiation helicity are calculated. It is demonstrated that the frequency dependence of the magnetic ratchet currents is determined by the dominant elastic-scattering mechanism of two-dimensional carriers and differs for the systems with linear and parabolic energy dispersions.

  18. Hypervelocity orbital intercept guidance

    NASA Astrophysics Data System (ADS)

    Alfano, Salvatore

    1988-04-01

    Terminal guidance of a hypervelocity exo-atmospheric orbital interceptor with free end-time is examined. The pursuer is constrained to lateral thrusting with the evader modeled as an ICBM in its final boost phase. Proportional navigation, optimal control using certainty equivalence, dual control, and control with optimum thrust spacing are all examined. Also, a new approach called certainty control is developed for this problem. This algorithm constrains the final state to a function of projected estimate error to reduce control energy expenditure. All methods model the trajectories using splines and employ eight state Extended Kalman Filters with line-of-sight and range updates. The relative effectiveness of these control strategies is illustrated by applying them to various intercept problems.

  19. Exploratory orbit analysis

    SciTech Connect

    Michelotti, L.

    1989-03-01

    Unlike the other documents in these proceedings, this paper is neither a scientific nor a technical report. It is, rather, a short personal essay which attempts to describe an Exploratory Orbit Analysis (EOA) environment. Analyzing the behavior of a four or six dimensional nonlinear dynamical system is at least as difficult as analyzing events in high-energy collisions; the consequences of doing it badly, or slowly, would be at least as devastating; and yet the level of effort and expenditure invested in the latter, the very attention paid to it by physicists at large, must be two orders of magnitude greater than that given to the former. It is difficult to choose the model which best explains the behavior of a physical device if one does not first understand the behavior of the available models. The time is ripe for the development of a functioning EOA environment, which I will try to describe in this paper to help us achieve this goal.

  20. Skylab Orbiter Workshop Illustration

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This cutaway illustration shows the characteristics and basic elements of the Skylab Orbiter Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment. The compartment below the crew quarters was a container for liquid and solid waste and trash accumulated throughout the mission. A solar array, consisting of two wings covered on one side with solar cells, was mounted outside the workshop to generate electrical power to augment the power generated by another solar array mounted on the solar observatory. Thrusters were provided at one end of the workshop for short-term control of the attitude of the space station.

  1. PyORBIT: A Python Shell For ORBIT

    SciTech Connect

    Jean-Francois Ostiguy; Jeffrey Holmes

    2003-07-01

    ORBIT is code developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. The code is structured as a collection of external C++ modules for SuperCode, a high level interpreter shell developed at LLNL in the early 1990s. SuperCode is no longer actively supported and there has for some time been interest in replacing it by a modern scripting language, while preserving the feel of the original ORBIT program. In this paper, we describe a new version of ORBIT where the role of SuperCode is assumed by Python, a free, well-documented and widely supported object-oriented scripting language. We also compare PyORBIT to ORBIT from the standpoint of features, performance and future expandability.

  2. SIRTF in high earth orbit

    NASA Technical Reports Server (NTRS)

    Werner, Michael W.; Brooks, Walter F.; Manning, Larry A.; Eisenhardt, Peter

    1989-01-01

    The goals, requirements and operation of the Space Infrared Telescope Facility (SIRTF) are discussed. Emphasis is upon an analysis of the options of high and low earth orbits for the mission. The consensus was that the high earth orbit offers significant scientific and engineering advantages for SIRTF.

  3. LROC - Lunar Reconnaissance Orbiter Camera

    Microsoft Academic Search

    M. S. Robinson; E. Bowman-Cisneros; S. M. Brylow; E. Eliason; H. Hiesinger; B. L. Jolliff; A. S. McEwen; M. C. Malin; D. Roberts; P. C. Thomas; E. Turtle

    2006-01-01

    The Lunar Reconnaissance Orbiter Camera (LROC) is designed to address two of the prime LRO measurement requirements. 1) Assess meter and smaller-scale features to facilitate safety analysis for potential lunar landing sites near polar resources, and elsewhere on the Moon. 2) Acquire multi-temporal synoptic imaging of the poles every orbit to characterize the polar illumination environment (100 m scale), identifying

  4. Orbit propagation in Minkowskian geometry

    NASA Astrophysics Data System (ADS)

    Roa, Javier; Peláez, Jesús

    2015-06-01

    The geometry of hyperbolic orbits suggests that Minkowskian geometry, and not Euclidean, may provide the most adequate description of the motion. This idea is explored in order to derive a new regularized formulation for propagating arbitrarily perturbed hyperbolic orbits. The mathematical foundations underlying Minkowski space-time {M} are exploited to describe hyperbolic orbits. Hypercomplex numbers are introduced to define the rotations, vectors, and metrics in the problem: the evolution of the eccentricity vector is described on the Minkowski plane {R}_1^2 in terms of hyperbolic numbers, and the orbital plane is described on the inertial reference using quaternions. A set of eight orbital elements is introduced, namely a time-element, the components of the eccentricity vector in {R}_1^2 , the semimajor axis, and the components of the quaternion defining the orbital plane. The resulting formulation provides a deep insight into the geometry of hyperbolic orbits. The performance of the formulation in long-term propagations is studied. The orbits of four hyperbolic comets are integrated and the accuracy of the solution is compared to other regularized formulations. The resulting formulation improves the stability of the integration process and it is not affected by the perihelion passage. It provides a level of accuracy that may not be reached by the compared formulations, at the cost of increasing the computational time.

  5. Orbital evolution around irregular bodies

    Microsoft Academic Search

    A. Rossi; F. Marzari; P. Farinella

    1999-01-01

    The new profiles of the space missions aimed at asteroids and comets, moving from fly-bys to rendezvous and orbiting, call for new spaceflight dynamics tools capable of propagating orbits in an accurate way around these small irregular objects. Moreover, interesting celestial mechanics and planetary science problems, requiring the same sophisticated tools, have been raised by the first images of asteroids

  6. Endoscopic treatment of orbital tumors.

    PubMed

    Signorelli, Francesco; Anile, Carmelo; Rigante, Mario; Paludetti, Gaetano; Pompucci, Angelo; Mangiola, Annunziato

    2015-03-16

    Different orbital and transcranial approaches are performed in order to manage orbital tumors, depending on the location and size of the lesion within the orbit. These approaches provide a satisfactory view of the superior and lateral aspects of the orbit and the optic canal but involve risks associated with their invasiveness because they require significant displacement of orbital structures. In addition, external approaches to intraconal lesions may also require deinsertion of extraocular muscles, with subsequent impact on extraocular mobility. Recently, minimally invasive techniques have been proposed as valid alternative to external approaches for selected orbital lesions. Among them, transnasal endoscopic approaches, "pure" or combined with external approaches, have been reported, especially for intraconal lesions located inferiorly and medially to the optic nerve. The avoidance of muscle detachment and the shortness of the surgical intraorbital trajectory makes endoscopic approach less invasive, thus minimizing tissue damage. Endoscopic surgery decreases the recovery time and improves the cosmetic outcome not requiring skin incisions. The purpose of this study is to review and discuss the current surgical techniques for orbital tumors removal, focusing on endoscopic approaches to the orbit and outlining the key anatomic principles to follow for safe tumor resection. PMID:25789299

  7. What is a MISR orbit?

    Atmospheric Science Data Center

    2014-12-08

    ... on a sun-synchronous orbit. It revolves once around the planet in 98.88 minutes and thus completes about 14.5 revolutions per day. In ... the Terra platform is over the illuminated (day) side of the planet, i.e., during one half of the complete orbit or a bit less. Of course, ...

  8. Orbit determination in satellite geodesy

    Microsoft Academic Search

    G. Beutler; T. Schildknecht; U. Hugentobler; W. Gurtner

    2003-01-01

    For centuries orbit determination in Celestial Mechanics was a synonym for the determination of six so-called Keplerian elements of the orbit of a minor planet or a comet based on a short series of (three or more) astrometric places observed from one or more observatories on the Earth's surface. With the advent of the space age the problem changed considerably

  9. Safety in earth orbit study

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Safety aspects are studied of the space shuttle orbiter, the shuttle payloads, and space stations in earth orbital operations. The tasks generated safety requirements, guidelines, recommendations, and conceptual safety devices. The tasks studied were: hazardous payloads, docking, onboard survivability tumbling spacecraft, and escape and rescue operations.

  10. Interacting Binaries with Eccentric Orbits

    Microsoft Academic Search

    Jeremy F. Sepinsky; B. Willems; V. Kalogera

    2006-01-01

    The Roche model has served for a long time as a fundamental tool to study the interactions and observational characteristics of the components of gravitational two-body systems. More often than not, applications of this model are built on the assumption that the orbit of the system is circular and that the system components are rotating synchronously with the orbital motion.

  11. Endoscopic treatment of orbital tumors

    PubMed Central

    Signorelli, Francesco; Anile, Carmelo; Rigante, Mario; Paludetti, Gaetano; Pompucci, Angelo; Mangiola, Annunziato

    2015-01-01

    Different orbital and transcranial approaches are performed in order to manage orbital tumors, depending on the location and size of the lesion within the orbit. These approaches provide a satisfactory view of the superior and lateral aspects of the orbit and the optic canal but involve risks associated with their invasiveness because they require significant displacement of orbital structures. In addition, external approaches to intraconal lesions may also require deinsertion of extraocular muscles, with subsequent impact on extraocular mobility. Recently, minimally invasive techniques have been proposed as valid alternative to external approaches for selected orbital lesions. Among them, transnasal endoscopic approaches, “pure” or combined with external approaches, have been reported, especially for intraconal lesions located inferiorly and medially to the optic nerve. The avoidance of muscle detachment and the shortness of the surgical intraorbital trajectory makes endoscopic approach less invasive, thus minimizing tissue damage. Endoscopic surgery decreases the recovery time and improves the cosmetic outcome not requiring skin incisions. The purpose of this study is to review and discuss the current surgical techniques for orbital tumors removal, focusing on endoscopic approaches to the orbit and outlining the key anatomic principles to follow for safe tumor resection. PMID:25789299

  12. Floating orbital molecular dynamics simulations.

    PubMed

    Perlt, Eva; Brüssel, Marc; Kirchner, Barbara

    2014-04-21

    We introduce an alternative ab initio molecular dynamics simulation as a unification of Hartree-Fock molecular dynamics and the floating orbital approach. The general scheme of the floating orbital molecular dynamics method is presented. Moreover, a simple but sophisticated guess for the orbital centers is provided to reduce the number of electronic structure optimization steps at each molecular dynamics step. The conservation of total energy and angular momentum is investigated in order to validate the floating orbital molecular dynamics approach with and without application of the initial guess. Finally, a water monomer and a water dimer are simulated, and the influence of the orbital floating on certain properties like the dipole moment is investigated. PMID:24600690

  13. Optical astronomy from orbiting observatories

    NASA Astrophysics Data System (ADS)

    Perry, P. M.; Whitman, W. R.

    In order to avoid the factors affecting ground-based observations which degrade resolution and limit reach (atmospheric extinction, seeing, and light pollution), astronomical telescopes were moved into earth orbit. This move also solved the problem of atmospheric absorption of radiation shorter than 0.3 microns. The success of the first series of orbiting observatories, the Orbiting Astronomical Observatories (OAO) established the satellites as one of a new generation of tools for exploring the universe. The International Ultraviolet Explorer (IUE), launched in a geosynchronous orbit (1978), provided a guest observer facility serving the international community. In 1980, nearly 30% of the observational papers published in the Astrophysical Journal dealt with satellite data, and nearly one out of three of those papers used results from the IUE. The Space Telescope (ST), the newest orbiting observatory, is currently scheduled for launch in January, 1985. A detailed description of the OAOs, the IUE, and the ST are given, along with their scientific objectives and performances.

  14. Lifetime of objects in geostationary transfer orbit

    Microsoft Academic Search

    G. Janin

    1991-01-01

    Objects in Geostationary Transfer Orbit (GTO) result from the launch of satellites in geostationary orbit. There are close to 200 GTO, most of them third stage rockets used for transferring satellites from low Earth orbit to geostationary orbit. By crossing the low Earth orbit region at high speed more than twice a day, they represent a hazard for low Earth

  15. Low Earth Orbiter: Terminal

    NASA Technical Reports Server (NTRS)

    Kremer, Steven E.; Bundick, Steven N.

    1999-01-01

    In response to the current government budgetary environment that requires the National Aeronautics and Space Administration (NASA) to do more with less, NASA/Goddard Space Flight Center's Wallops Flight Facility has developed and implemented a class of ground stations known as a Low Earth Orbiter-Terminal (LEO-T). This development thus provides a low-cost autonomous ground tracking service for NASA's customers. More importantly, this accomplishment provides a commercial source to spacecraft customers around the world to purchase directly from the company awarded the NASA contract to build these systems. A few years ago, NASA was driven to provide more ground station capacity for spacecraft telemetry, tracking, and command (TT&C) services with a decreasing budget. NASA also made a decision to develop many smaller, cheaper satellites rather than a few large spacecraft as done in the past. In addition, university class missions were being driven to provide their own TT&C services due to the increasing load on the NASA ground-tracking network. NASA's solution for this ever increasing load was to use the existing large aperture systems to support those missions requiring that level of performance and to support the remainder of the missions with the autonomous LEO-T systems. The LEO-T antenna system is a smaller, cheaper, and fully autonomous unstaffed system that can operate without the existing NASA support infrastructure. The LEO-T provides a low-cost, reliable space communications service to the expanding number of low-earth orbiting missions around the world. The system is also fostering developments that improve cost-effectiveness of autonomous-class capabilities for NASA and commercial space use. NASA has installed three LEO-T systems. One station is at the University of Puerto Rico, the second system is installed at the Poker Flat Research Range near Fairbanks, Alaska, and the third system is installed at NASA's Wallops Flight Facility in Virginia. This paper will describe the current NASA implementation of the LEO-T network of antenna systems, the customers now being supported, and the services NASA can now offer with this new breed of autonomous ground stations. In addition, the paper will define the technical capabilities of the system and the cost effectiveness of using the systems including the capital costs of installation.

  16. GPS orbit processing in support of low earth orbiter precise orbit determination

    Microsoft Academic Search

    I. Romero; H. Boomkamp; J. Dow; C. Garcia

    2003-01-01

    There are currently an increasing number of LEO missions incorporating dual frequency GPS receivers for Satellite to Satellite Tracking. The majority of LEO precise orbit determination (POD) strategies rely on high quality GPS orbits and clocks such as those supplied by the IGS Final product. The availability of these products may not satisfy operational requirements due to their ten day

  17. The Lunar Orbiter program

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The Luna and Zond series of unmanned U.S.S.R. spacecraft were designed to investigate the moon and its vicinity. Sixteen Luna spacecraft and, six Zond spacecraft have obtained lunar data. These series have included flyby, lunar-orbiting, and soft-landing missions. A variety of experiments were carried out by these spacecraft including studies of magnetism, X-ray and gamma emissions, gravitational anomalies, and chemical composition. Soil samples, near- and farside photography (both color and black and white), and earth-cloud photography were also acquired. Luna 17 and 23, carried automatic roving vehicles (Lunokhod 1 and 2) that traversed portions of the lunar surface. Lunokhod 1 roamed in Mare Imbrium near Sinus Iridum, and Lunokhod 2 roamed in the Crater Le Monnier at the eastern edge of Mare Serenitatis. The Luna 16, 20, and 24 missions soft-landed on the lunar surface, scooped up lunar material, and returned these samples to earth. The photographic samples received are in the form of paper prints. Some publications containing photographs are described.

  18. Orbiter Camera Payload System

    NASA Astrophysics Data System (ADS)

    1980-12-01

    Components for an orbiting camera payload system (OCPS) include the large format camera (LFC), a gas supply assembly, and ground test, handling, and calibration hardware. The LFC, a high resolution large format photogrammetric camera for use in the cargo bay of the space transport system, is also adaptable to use on an RB-57 aircraft or on a free flyer satellite. Carrying 4000 feet of film, the LFC is usable over the visible to near IR, at V/h rates of from 11 to 41 milliradians per second, overlap of 10, 60, 70 or 80 percent and exposure times of from 4 to 32 milliseconds. With a 12 inch focal length it produces a 9 by 18 inch format (long dimension in line of flight) with full format low contrast resolution of 88 lines per millimeter (AWAR), full format distortion of less than 14 microns and a complement of 45 Reseau marks and 12 fiducial marks. Weight of the OCPS as supplied, fully loaded is 944 pounds and power dissipation is 273 watts average when in operation, 95 watts in standby. The LFC contains an internal exposure sensor, or will respond to external command. It is able to photograph starfields for inflight calibration upon command.

  19. Orbiter Camera Payload System

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Components for an orbiting camera payload system (OCPS) include the large format camera (LFC), a gas supply assembly, and ground test, handling, and calibration hardware. The LFC, a high resolution large format photogrammetric camera for use in the cargo bay of the space transport system, is also adaptable to use on an RB-57 aircraft or on a free flyer satellite. Carrying 4000 feet of film, the LFC is usable over the visible to near IR, at V/h rates of from 11 to 41 milliradians per second, overlap of 10, 60, 70 or 80 percent and exposure times of from 4 to 32 milliseconds. With a 12 inch focal length it produces a 9 by 18 inch format (long dimension in line of flight) with full format low contrast resolution of 88 lines per millimeter (AWAR), full format distortion of less than 14 microns and a complement of 45 Reseau marks and 12 fiducial marks. Weight of the OCPS as supplied, fully loaded is 944 pounds and power dissipation is 273 watts average when in operation, 95 watts in standby. The LFC contains an internal exposure sensor, or will respond to external command. It is able to photograph starfields for inflight calibration upon command.

  20. Space Telescopes and Orbital Debris

    NASA Astrophysics Data System (ADS)

    Seitzer, Patrick

    2009-01-01

    Almost 12,000 artificial objects orbiting the Earth are currently in the public catalog of orbital elements maintained by the USAF. Only a small fraction of them are operational satellites. The remainder is satellites whose missions have ended, rocket bodies, and parts and debris from larger parent objects. And the catalog only contains the biggest and brightest of the objects in orbit. The Low Earth Orbit (LEO) regime where most of this population concentrates is also a regime of incredible interest to astronomers, since it is where flagship missions such as the Hubble Space Telescope and other Great Observatories operate. I'll review the current state of knowledge of the orbital debris population, how it has grown with time, and how this environment could affect current and future space telescopes. There are mitigation measures which many spacecraft operators have adopted which can control the growth of the debris population. Orbital debris research at the University of Michigan is funded by NASA's Orbital Debris Program Office, Johnson Space Center, Houston, Texas.

  1. Mapping Elliptical Orbits Around Europa

    NASA Astrophysics Data System (ADS)

    Vilhena de Moraes, Rodolpho; Prado, Antonio; Carvalho, Jean Paulo; Cardoso dos Santos, Josué

    Due to specifics scientific purposes space missions has been proposed to explore natural satellites, comets and asteroids sending artificial satellites orbiting around these bodies. The planning of such missions must be taken into account a good choice for the orbits that reduces the cost related to station-keeping and the increasing the duration of the mission. The present research has the objective of using a new concept to map with respect the station-keeping maneuvers to study elliptical orbits around Europa. This concept is based in the integral of the perturbing forces over the time. This value can estimate the total variation of velocity received by the spacecraft from the perturbations forces acting on it. The value of this integral is a characteristic of the perturbations considered and the orbit chosen for the spacecraft. Numerical simulations are made showing the value of this integral for orbits around Europa as a function of the eccentricity and semi-major axis of the orbits. An important application of the present research is in the search for frozen orbits.

  2. Radiation therapy for orbital lymphoma

    SciTech Connect

    Zhou Ping [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States)]. E-mail: pzhou@partners.org; Ng, Andrea K. [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Silver, Barbara [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Li Sigui [Department of Biostatistical Sciences, Dana-Farber Cancer Institute, Boston, MA (United States); Hua Ling [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States); Mauch, Peter M. [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA (United States)

    2005-11-01

    Purpose: To describe radiation techniques and evaluate outcomes for orbital lymphoma. Methods and Materials: Forty-six patients (and 62 eyes) with orbital lymphoma treated with radiotherapy between 1987 and 2003 were included. The majority had mucosa-associated lymphoid tissue (48%) or follicular (30%) lymphoma. Seventeen patients had prior lymphoma at other sites, and 29 had primary orbital lymphoma. Median follow-up was 46 months. Results: The median dose was 30.6 Gy; one-third received <30 Gy. Electrons were used in 9 eyes with disease confined to the conjunctiva or eyelid, and photons in 53 eyes with involvement of intraorbital tissues to cover entire orbit. Local control rate was 98% for all patients and 100% for those with indolent lymphoma. Three of the 26 patients with localized primary lymphoma failed distantly, resulting in a 5-year freedom-from-distant-relapse rate of 89%. The 5-year disease-specific and overall survival rates were 95% and 88%, respectively. Late toxicity was mainly cataract formation in patients who received radiation without lens block. Conclusions A dose of 30 Gy is sufficient for indolent orbital lymphoma. Distant relapse rate in patients with localized orbital lymphoma was lower than that reported for low-grade lymphoma presenting in other sites. Orbital radiotherapy can be used for salvage of recurrent indolent lymphoma.

  3. Orbital metastases: diagnosis and course

    PubMed Central

    Char, D.; Miller, T.; Kroll, S.

    1997-01-01

    AIMS—Three issues were investigated in adult outpatients with orbital metastases. One, how accurate are current diagnostic methods? Two, what is the survival associated with orbital metastases? Three, did any clinical factors correlate with prognosis in this patient cohort??METHODS—Retrospective analysis of patients with orbital metastases managed in an ocular oncology unit.?RESULTS—11 of 31 (35%) patients had no known primary malignancy at the time of orbital diagnosis. In eight of 31 (26%) computed tomography and/or magnetic resonance imaging data did not yield the diagnosis of metastases. In 15 of 17 (88%) cases a fine needle aspiration biopsy was diagnostic. Several types of therapy were used. The median survival was 1.3 years.?CONCLUSION—Orbital metastases, even with newer diagnostic techniques can be difficult to diagnose. Management was based on location and extent of both orbital and systemic disease as well as vision. In most cases, orbital symptoms were palliated; however, survival was dismal. No clinical factor correlated with prognosis.?? PMID:9227204

  4. Orbital, Rotational, and Climatic Interactions

    NASA Technical Reports Server (NTRS)

    Bills, Bruce G. (editor)

    1992-01-01

    The report of an international meeting on the topic of Orbital, Rotational, and Climatic Interactions, which was held 9-11 Jul. 1991 at the Johns Hopkins University is presented. The meeting was attended by 22 researchers working on various aspects of orbital and rotational dynamics, paleoclimate data analysis and modeling, solid-Earth deformation studies, and paleomagnetic analyses. The primary objective of the workshop was to arrive at a better understanding of the interactions between the orbital, rotational, and climatic variations of the Earth. This report contains a brief introduction and 14 contributed papers which cover most of the topics discussed at the meeting.

  5. Extrasolar Planet Orbits and Eccentricities

    E-print Network

    Scott Tremaine; Nadia L. Zakamska

    2003-12-01

    The known extrasolar planets exhibit many interesting and surprising features--extremely short-period orbits, high-eccentricity orbits, mean-motion and secular resonances, etc.--and have dramatically expanded our appreciation of the diversity of possible planetary systems. In this review we summarize the orbital properties of extrasolar planets. One of the most remarkable features of extrasolar planets is their high eccentricities, far larger than seen in the solar system. We review theoretical explanations for large eccentricities and point out the successes and shortcomings of existing theories.

  6. Mars Science Laboratory Orbit Determination

    NASA Technical Reports Server (NTRS)

    Kruizinga, Gerhard L.; Gustafson, Eric D.; Thompson, Paul F.; Jefferson, David C.; Martin-Mur, Tomas J.; Mottinger, Neil A.; Pelletier, Frederic J.; Ryne, Mark S.

    2012-01-01

    This paper describes the orbit determination process, results and filter strategies used by the Mars Science Laboratory Navigation Team during cruise from Earth to Mars. The new atmospheric entry guidance system resulted in an orbit determination paradigm shift during final approach when compared to previous Mars lander missions. The evolving orbit determination filter strategies during cruise are presented. Furthermore, results of calibration activities of dynamical models are presented. The atmospheric entry interface trajectory knowledge was significantly better than the original requirements, which enabled the very precise landing in Gale Crater.

  7. Mab's orbital motion explained

    NASA Astrophysics Data System (ADS)

    Kumar, K.; de Pater, I.; Showalter, M. R.

    2015-07-01

    We explored the hypothesis that Mab's anomalous orbital motion, as deduced from Hubble Space Telescope (HST) data (Showalter, M.R., Lissauer, J.J. [2006]. Science (New York, NY) 311, 973-977), is the result of gravitational interactions with a putative suite of large bodies in the ?-ring. We conducted simulations to compute the gravitational effect of Mab (a recently discovered Uranian moon) on a cloud of test particles. Subsequently, by employing the data extracted from the test particle simulations, we executed random walk simulations to compute the back-reaction of nearby perturbers on Mab. By generating simulated observation metrics, we compared our results to the data retrieved from the HST. Our results indicate that the longitude residual change noted in the HST data (??r,Mab ? 1 deg) is well matched by our simulations. The eccentricity variations (?eMab ?10-3) are however typically two orders of magnitude too small. We present a variety of reasons that could account for this discrepancy. The nominal scenario that we investigated assumes a perturber ring mass (mring) of 1 mMab (Mab's mass) and a perturber ring number density (?n,ring) of 10 perturbers per 3 RHill,Mab (Mab's Hill radius). This effectively translates to a few tens of perturbers with radii of approximately 2-3 km, depending on the albedo assumed. The results obtained also include an interesting litmus test: variations of Mab's inclination on the order of the eccentricity changes should be observable. Our work provides clues for further investigation into the tantalizing prospect that the Mab/?-ring system is undergoing re-accretion after a recent catastrophic disruption.

  8. Orbital Maneuvering system design evolution

    NASA Technical Reports Server (NTRS)

    Gibson, C.; Humphries, C.

    1985-01-01

    Preliminary design considerations and changes made in the baseline space shuttle orbital maneuvering system (OMS) to reduce cost and weight are detailed. The definition of initial subsystem requirements, trade studies, and design approaches are considered. Design features of the engine, its injector, combustion chamber, nozzle extension and bipropellant valve are illustrated and discussed. The current OMS consists of two identical pods that use nitrogen tetroxide (NTO) and monomethylhydrazine (MMH) propellants to provide 1000 ft/sec of delta velocity for a payload of 65,000 pounds. Major systems are pressurant gas storage and control, propellant storage supply and quantity measurement, and the rocket engine, which includes a bipropellant valve, an injector/thrust chamber, and a nozzle. The subsystem provides orbit insertion, circularization, and on orbit and deorbit capability for the shuttle orbiter.

  9. NASA Orbital Debris Baseline Populations

    NASA Technical Reports Server (NTRS)

    Krisko, Paula H.; Vavrin, A. B.

    2013-01-01

    The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

  10. Visualization of Molecular Orbitals: Formaldehyde

    ERIC Educational Resources Information Center

    Olcott, Richard J.

    1972-01-01

    Describes a computer program that plots a solid" representation of molecular orbital charge density which can be used to analyze wave functions of molecules. Illustrated with diagrams for formaldehyde. (AL)

  11. Orbital evolution of some Centaurs

    NASA Astrophysics Data System (ADS)

    Kovalenko, Nataliya; Babenko, Yuri; Churyumov, Klim

    2002-11-01

    In this work we investigated the dynamical evolution of Centaurs objects 2060 (Chiron), 5145 (Pholus), 7066 (Nessus), 8405 (Asbolus), 10199 (Chariklo), 10370 (Hylonome), and Scattered-Disk object 15874. We have carried out orbital integration of test particles with initial orbits similar to those of these objects. Calculations were produced for +/-600kyr-10Myr starting at epoch and using the implicit single sequence Everhart methods. 12 variational orbits for each of selected Centaurs also have been numerically integrated for +/-200 kyr toward the past and the future. The most probable paths were traced up to +/-1 Myr. The character of orbital elements changes and peculiarities of close approaches to giant planets are discussed.

  12. Real and Hybrid Atomic Orbitals.

    ERIC Educational Resources Information Center

    Cook, D. B.; Fowler, P. W.

    1981-01-01

    Demonstrates that the Schrodinger equation for the hydrogenlike atom separates in both spheroconal and prolate spheroidal coordinates and that these separations provide a sound theoretical basis for the real and hybrid atomic orbitals. (Author/SK)

  13. Pioneer Venus Orbiter Fluxgate Magnetometer

    Microsoft Academic Search

    C. T. Russell; R. C. Snare; J. D. Means; R. C. Elphic

    1980-01-01

    The fluxgate magnetometer on the Pioneer Venus orbiter spacecraft is described. Special features include gradiometer operation, on board despinning, a floating point processor and variable Nyquist filters. Initial operations have been entirely successful.

  14. Epithelioid hemangioma of the orbit

    Microsoft Academic Search

    Todd M McEachren; Seymour Brownstein; David R Jordan; Vital A Montpetit

    2000-01-01

    ObjectiveTo describe the histopathologic features of two cases of epithelioid hemangioma occurring in the orbit and to distinguish this condition from Kimura’s disease and from other vascular lesions of proliferated endothelium.

  15. A Case of Orbital Histoplasmosis.

    PubMed

    Krakauer, Mark; Prendes, Mark Armando; Wilkes, Byron; Lee, Hui Bae Harold; Fraig, Mostafa; Nunery, William R

    2014-09-01

    Histoplasma capsulatum var capsulatum is a dimorphic fungus endemic to the Ohio and Mississippi River Valleys of the United States. In this case report, a 33-year-old woman who presented with a right orbital mass causing progressive vision loss, diplopia, and facial swelling is described. Lateral orbitotomy with lateral orbital wall bone flap was performed for excisional biopsy of the lesion. The 1.5 × 1.8 × 2.3 cm cicatricial mass demonstrated a granulomatous lesion with necrosis and positive staining consistent with Histoplasma capsulatum var capsulatum infection. To the authors' knowledge, this is the first case of orbital histoplasmosis to be reported in the United States and the first case worldwide of orbital histoplasmosis due to Histoplasma capsulatum var capsulatum. PMID:25186215

  16. Lunar orbital mass spectrometer experiment

    NASA Technical Reports Server (NTRS)

    Lord, W. P.

    1971-01-01

    The design, development, manufacture, test and calibration of five lunar orbital mass spectrometers with the four associated ground support equipment test sets are discussed. A mass spectrometer was installed in the Apollo 15 and one in the Apollo 16 Scientific Instrument Module within the Service Module. The Apollo 15 mass spectrometer was operated with collection of 38 hours of mass spectra data during lunar orbit and 50 hours of data were collected during transearth coast. The Apollo 16 mass spectrometer was operated with collection of 76 hours of mass spectra data during lunar orbit. However, the Apollo 16 mass spectrometer was ejected into lunar orbit upon malfunction of spacecraft boom system just prior to transearth insection and no transearth coast data was possible.

  17. LROC - Lunar Reconnaissance Orbiter Camera

    Microsoft Academic Search

    M. S. Robinson; E. Eliason; H. Hiesinger; B. L. Jolliff; A. McEwen; M. C. Malin; M. A. Ravine; P. C. Thomas; E. P. Turtle

    2009-01-01

    The Lunar Reconnaissance Orbiter (LRO) went into lunar orbit on 23 June 2009. The LRO Camera (LROC) acquired its first lunar images on June 30 and commenced full scale testing and commissioning on July 10. The LROC consists of two narrow-angle cameras (NACs) that provide 0.5 m scale panchromatic images over a combined 5 km swath, and a wide-angle camera

  18. Orbits in a logarithmic potential

    SciTech Connect

    Hooverman, R.H.

    2014-04-15

    The characteristics of charged particle orbits in the logarithmic electrostatic potential field surrounding a straight conducting wire at a fixed potential are investigated. The equations of motion of an electron in a logarithmic potential are derived, the limiting cases are considered, and the results of numerical integration of the equations of motion are presented along with sketches of a few representative orbits. (C.E.S.)

  19. The Earth and Moon's Orbit

    NSDL National Science Digital Library

    2009-02-28

    The following activities will help you explore how the earth and moon move around the sun. Activity 1: Go to the following activity below and then answer the questions below in your science journal. The Earth s Orbit Activity 1) How many months did it take to get the earth to orbit the sun one time? 2) Describe the motion of the earth and moon as it traveled around the sun? 3) How many hours ...

  20. Orbital Debris Studies at NASA

    NASA Technical Reports Server (NTRS)

    Stansbery, Gene; Krisko, Paula; Whitlock, Dave

    2007-01-01

    Any discussion of expanding the capabilities of Space Surveillance Networks to include tracking and cataloging smaller objects will require a good understanding of orbital debris. In the current U.S. catalog of over 11,000 objects, more than 50% are classified as "debris" to include fragmentation debris, operational debris, liquid metal coolant, and Westford needles. If the catalog is increased to 100,000 objects by lowering the tracked object size threshold, almost all of the additional objects will be orbital debris. The Orbital Debris Program Office has been characterizing the small orbital debris environment through measurements and modeling for many years. This presentation will specifically discuss two different studies conducted at NASA. The first study was done in 1992 and examined the requirements and produced a conceptual design for a Collision Avoidance Network to protect the Space Station Freedom from centimeter sized orbital debris while minimizing maneuvers. The second study was conducted last year and produced NASA s estimate of the orbital population for the years 2015 and 2030 for objects 2 cm and larger.

  1. Low Earth orbit communications satellite

    NASA Technical Reports Server (NTRS)

    Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

    1992-01-01

    A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

  2. Dynamics of Earth orbiting formations

    NASA Technical Reports Server (NTRS)

    Ploen, Scott R.; Scharf, Daniel P.; Hadaegh, Fred Y.; Acikmese, Ahmed B.

    2004-01-01

    In this paper the equations of motion of a formation consisting of n spacecraft in Earth orbit are derived via Lagrange's equations. The equations of motion of the formation are developed with respect to both (1) a bound Keplerian reference orbit, and (2) a specific spacecraft in the formation. The major orbital perturbations acting on a formation in low Earth orbit are also included in the analysis. In contrast to the traditional approach based on the balance of linear momentum, the use of Lagrange's equations leads to a high-level matrix derivation of the formation equations of motion. The matrix form of the nonlinear motion equations is then linearized about a bound Keplerian reference orbit. Next, it is demonstrated that under the assumption of a circular reference orbit, the linearized equations of motion reduce to the well-known Hill-Clohessy-Wiltshire equations. The resulting linear and nonlinear dynamic equations lead to maximal physical insight into the structure of formation dynamics, and are ideally suited for use in the design and validation of formation guidance and control laws.

  3. Precise orbit determination for GRACE

    NASA Astrophysics Data System (ADS)

    Kang, Z.; Nagel, P.; Pastor, R.

    2003-04-01

    The twin, co-orbiting GRACE (Gravity Recovery and Climate Experiment) satellites were launched in March 2002. The primary objective of the GRACE mission is to determine the Earth's gravity field and its temporal variations with unprecedented accuracy. To satisfy this objective as well as other applications (e.g. atmospheric profiling by radio occultation), accurate orbits for GRACE are required. This paper describes several results related to the use of the data collected by the GRACE GPS receiver, high precision accelerometer observations and precise attitude data from star trackers in the application of the GRACE Precise Orbit Determination (POD). The orbit accuracy is assessed using a number of tests, which include analysis of GPS tracking observation residuals, Satellite Laser Ranging (SLR) residuals, K-Band Ranging (KBR) residuals and external orbit comparisons. The results show that an accuracy of better than 5 cm in each direction for GRACE orbits can be obtained. The relative accuracy of the two GRACE satellites is about 1 cm in position and 10 micrometers per second in velocity.

  4. Aiming at a 1-cm Orbit for Low Earth Orbiters: Reduced-Dynamic and Kinematic Precise Orbit Determination

    Microsoft Academic Search

    P. N. A. M. Visser; J. van den Ijssel

    2003-01-01

    The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP, GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at the few cm level. Such a level of accuracy might be achieved with the techniques of reduced-dynamic and kinematic precise orbit

  5. Tribochemistry of ZDDP in molecular orbital calculations

    Microsoft Academic Search

    Yuanqiang Tan; Weijiu Huang; Xueye Wang

    2004-01-01

    The molecular orbital parameters of zinc dialkyldithiophosphate (ZDDP) and several metal-atom-cluster models were calculated. The nature and the strength of the interactions between the ZDDP molecules and different metal surfaces are analysed and discussed with the use of frontier orbital theory. By comparing the highest occupied molecular orbital energy (EHOMO) and the lowest unoccupied molecular orbital energy (ELUMO) of the

  6. Orbiting Low Frequency Array for Radio Astronomy

    E-print Network

    Langendoen, Koen

    either orbit the moon, whilst sampling during the Earth-radio eclipse phase, or orbit the Earth-moon L2 be implemented in moon orbit with today's technology. 1 #12;Number of satellites (or antennas) 10, scalableOrbiting Low Frequency Array for Radio Astronomy Raj Thilak Rajan ASTRON, Dwingeloo, NL rajan

  7. Orbital expansion of the congenitally anophthalmic socket.

    PubMed Central

    Tucker, S M; Sapp, N; Collin, R

    1995-01-01

    BACKGROUND--Congenital anophthalmos is a rare condition in which intervention at an early age can stimulate orbital expansion and maximise facial symmetry. Much is still unknown, however, regarding the degree of soft tissue and bony orbital growth achieved using the orbital expanders presently available. METHODS--A retrospective review of 59 congenitally anophthalmic orbits in 42 patients was carried out. RESULTS--The soft tissue and bony orbital expansion achieved using serial solid shapes is reported, and experience with hydrophilic expanders and inflatable silicone expanders is reviewed. CONCLUSION--Although serially fitted solid shapes in the orbit lead to increased expansion of orbital soft tissue and bone compared with no orbital implant, further orbital tissue enlargement is required. The inflatable silicone expander may allow more rapid and extensive orbital tissue expansion, but design changes are needed to achieve this. PMID:7662633

  8. The Eccentric Behavior of Nearly Frozen Orbits

    NASA Technical Reports Server (NTRS)

    Sweetser, Theodore H.; Vincent, Mark A.

    2013-01-01

    Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

  9. Mars Orbiter Most Likely Lost

    NSDL National Science Digital Library

    de Nie, Michael Willem.

    In an embarrassing setback to NASA, the Mars Climate Orbiter is believed lost. In the early hours of September 23, the orbiter fired its main engine to go in orbit around Mars and passed behind the planet, losing radio contact as planned. However, due to what was most likely a navigation error, the spacecraft did not resume contact and may have flown too close to the atmosphere and broken apart or burned up. The relatively inexpensive ($125 million) Climate Orbiter was launched in December 1998 to become the first interplanetary weather satellite, studying Martian weather for one Mars year (about two Earth years). It was also to serve as a relay station for five years, relaying information to and from the Mars Polar Lander, due to land on December 3, 1999. NASA, however, insists that the Polar Lander's mission can be accomplished independently and "the science return of that mission won't be affected." The sites listed provide information about Mars Climate Orbiter and its possible loss.

  10. Orbital schwannoma: a clinicopathologic study.

    PubMed

    Pushker, Neelam; Khurana, Saurbhi; Kashyap, Seema; Sen, Seema; Shrey, Dinesh; Meel, Rachna; Chawla, Bhavna; Bajaj, Mandeep S

    2015-08-01

    The aim of the study was to study the clinical, radiological and histopathological characteristics of orbital schwannomas. It is a retrospective study conducted at a tertiary eye care hospital. A review of histopathological records of the orbital tumors operated between 1993 and 2011 was done. The clinical, imaging and histopathological details of cases of orbital schwannoma were analyzed. Forty-nine cases of orbital schwannomas identified. The age ranged from 8 to 65 years with a female preponderance. The median duration of symptoms was 3 years. Computed tomography findings varied from a hypodense to hyperdense lesion with nil to marked contrast enhancement. USG demonstrated a defined lesion with variable internal reflectivity. Varied proportions of Antoni A and Antoni B areas were found on histopathology of the masses. Hypodense or cystic areas on imaging significantly correlated with Antoni B areas on histopathology. Orbital schwannoma is a rare tumor. The incidence of schwannoma in our institution is 6.5 %. Variable imaging features were found. The definite diagnosis can be established on the basis of histopathological and immunohistochemical studies. PMID:25052540

  11. The 2009 Mars Telecommunications Orbiter

    NASA Technical Reports Server (NTRS)

    Wilson, G. R.; DePaula, R.; Diehl, R. E.; Edwards, C. D.; Fitzgerald, R. J.; Franklin, S. F.; Kerridge, S. A.; Komarek, T. A.; Noreen, G. K.

    2004-01-01

    The first spacecraft with a primary function of providing communication links while orbiting a foreign planet has begun development for a launch in 2009. NASA's Mars Telecommunications Orbiter would use three radio bands to magnify the benefits of other future Mars missions and enable some types of missions otherwise impractical. It would serve as the Mars hub for a growing interplanetary Internet. And it would pioneer the use of planet-to-planet laser communications to demonstrate the possibility for even greater networking capabilities in the future. With Mars Telecommunications Orbiter overhead in the martian sky, the Mars Science Laboratory rover scheduled to follow the orbiter to Mars by about a month could send to Earth more than 100 times as much data per day as it could otherwise send. The orbiter will be designed for the capability of relaying up to 15 gigabits per day from the rover, equivalent to more than three full compact discs each day. The same benefits would accrue to other future major Mars missions from any nation.

  12. New Orbit Propagator to Be Used in Orbital Debris Evolutionary Models

    Microsoft Academic Search

    Tomohiro NARUMI; Toshiya HANADA

    2007-01-01

    An orbital environment debris evolutionary model for low Earth orbit has been developed at Kyushu University. A fast orbit propagator is essentially needed in such an evolutionary model because the number of space debris larger than 1 cm in low earth orbit is very large and it takes much time to compute long-term orbital changes of space debris. The effects

  13. Orbital extension of trigeminal schwannoma.

    PubMed

    Ghosh, Shantanu; Das, Debabrata; Varshney, Rahul; Nandy, Sumit

    2015-01-01

    Schwannomas, also known as neurilemmomas, are benign peripheral nerve sheath tumors. Trigeminal schwannomas are rare intracranial tumors. Here, we report a 35-year-old female presenting with an axial proptosis of right eyeball with right-sided III, IV and VI cranial nerve palsy. Her best corrected visual acuity in the right eye was perception of light absent and in the left eye was 20/20. MRI scan revealed a large right-sided heterogeneous, extra-axial middle cranial fossa mass that extended to the intraconal space of right orbit. A diagnosis of intracranial trigeminal nerve schwannoma with right orbital extension was made. Successful surgical excision of the mass with preservation of the surrounding tissues and orbital exenteration was done. Post-operative period was uneventful. PMID:25552864

  14. The Challenge of Orbital Debris

    NASA Technical Reports Server (NTRS)

    Matney, Mark

    2012-01-01

    Since the dawn of the Space Age more than 50 years ago, humans have been launching objects into the space environment faster than they have been removed by active means or natural decay. This has led to a proliferation of debris -- derelict satellites, discarded rocket upper stages, and pieces from satellite breakups -- in Earth orbit, especially in well-used orbital regimes. This talk will summarize the current knowledge of the debris environment and describe plans to address the challenges orbital debris raises for the future usability of near-Earth space. The talk will be structured around 4 categories: Measurements, Modeling, Shielding, and Mitigation. This will include discussions of the long-term prognosis of debris growth (i.e., the "Kessler Syndrome") as well as plans for active debris removal.

  15. Apollo 15 orbital science summary.

    NASA Technical Reports Server (NTRS)

    Esenwein, G. F.; Roberson, F. I.

    1972-01-01

    In this paper, summary results of the Apollo 15 orbital science payload are given, and some quick-look results of Apollo 16 are discussed. Geochemical instruments, consisting of gamma-ray, X-ray, and alpha particle spectrometers, have provided a chemical map of the lunar surface flown over by Apollo 15. The Laser Altimeter and frontside gravity data have shown some unexpected results with regard to the lunar shape, and provided new basis for understanding lunar mascons. A magnetometer, aboard the small subsatellite, has located magnetic anomalies principally on the lunar farside, and has shown that the small lunar magnetic field is smoother on the frontside than on the back. The mass spectrometer, in orbit aboard the Command and Service Modules, has measured unexpectedly large populations of molecules at orbital altitude (110 km), mostly due to spacecraft contamination. Two major camera systems have provided the first systematic metric quality photography and concurrent high resolution stereo coverage of the lunar surface.

  16. Orbital resonances in exoplanetary systems

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Shevchenko, I. I.

    2014-12-01

    At present, more than 700 exoplanetary systems are known to have been discovered. They incorporate more than 130 multiplanet systems, i.e. those hosting two or more planets. The orbital resonance and near-resonance phenomena are ubiquitous in them. We present a statistical and dynamical analysis of the resonance structure of the multiplanet systems and planetary systems of binary stars. We have built distributions of the orbital period ratios, separately considering the cases of inner and outer location of the massive perturber. The histograms reveal apparent peaks close to the first order orbital resonances 2/1 and 3/2 in both cases; this confirms previous findings. We have performed analytical modelling of the histograms, and obtained exact positions of the peaks. Moreover, we have built the "period ratio – eccentricity" diagrams, with collision curves superimposed, so that to find anomalous systems.

  17. Lunar orbital mass spectrometer experiment.

    NASA Technical Reports Server (NTRS)

    Hoffman, J. H.; Hodges, R. R., Jr.; Evans, D. E.

    1972-01-01

    One of the Orbital Science experiments on Apollo 15 was a mass spectrometer designed to measure the composition and distribution of the lunar atmosphere. It operated for nearly 90 hours, producing spectra of an unexpectedly complex nature, indicating that many complex gas molecules exist in the vicinity of the spacecraft. The most plausible explanation is that there was continual vaporization of frozen or liquid drops of water, fuel, or other matter that had been ejected from the spacecraft with small relative velocity so that these particles remained in nearby orbits. The search for naturally occurring gases in these spectra involves a statistical analysis of the data which has not been completed to date. A theoretical prediction regarding the possibilities of detecting lunar volcanism from orbit is included.

  18. Manned orbital space station studied

    NASA Astrophysics Data System (ADS)

    1982-08-01

    Operations of a proposed science and applications space platform (SASP) under consideration by NASA are described, including modifications of the STS to place larger payloads in orbit and also to add manned modules to the SASP. The platform is intended to provide power, data handling, a heat radiator, etc. for various instrument packages, thereby reducing the number of separate orbiting spacecraft. The SASP would also be equipped with a reboost module for compensating for the effects of gravity and atmospheric drag. Modifications to the system to provide a manned capacity include an airlock adaptor, a solar power system, and a habitat, besides a docking cylinder for the Orbiter. Further augmentations could be an emergency reentry vehicle similar to the Apollo, a three month supply of food, tools, and experimentation modules adapted from the Spacelab.

  19. Management of the orbital environment

    NASA Technical Reports Server (NTRS)

    Loftus, Joseph P., Jr.; Kessler, Donald J.; Anz-Meador, Phillip D.

    1991-01-01

    Data regarding orbital debris are presented to shed light on the requirements of environmental management in space, and strategies are given for active intervention and operational strategies. Debris are generated by inadvertent explosions of upper stages, intentional military explosions, and collisional breakups. Design and operation practices are set forth for minimizing debris generation and removing useless debris from orbit in the low-earth and geosynchronous orbits. Self-disposal options include propulsive maneuvers, drag-augmentation devices, and tether systems, and the drag devices are described as simple and passive. Active retrieval and disposition are considered, and the difficulty is examined of removing small debris. Active intervention techniques are required since pollution prevention is more effective than remediation for the problems of both earth and space.

  20. Orbital resonances around black holes.

    PubMed

    Brink, Jeandrew; Geyer, Marisa; Hinderer, Tanja

    2015-02-27

    We compute the length and time scales associated with resonant orbits around Kerr black holes for all orbital and spin parameters. Resonance-induced effects are potentially observable when the Event Horizon Telescope resolves the inner structure of Sgr A*, when space-based gravitational wave detectors record phase shifts in the waveform during the resonant passage of a compact object spiraling into the black hole, or in the frequencies of quasiperiodic oscillations for accreting black holes. The onset of geodesic chaos for non-Kerr spacetimes should occur at the resonance locations quantified here. PMID:25768747

  1. Rhino-orbital-cerebral mucormycosis.

    PubMed

    Gamaletsou, Maria N; Sipsas, Nikolaos V; Roilides, Emmanuel; Walsh, Thomas J

    2012-08-01

    This review focuses on sinus, sino-orbital, and rhinocerebral infection caused by the Mucorales. As the traditional term of "rhinocerebral" mucormycosis omits the critical involvement of the eye, the more comprehensive term as rhino-orbital-cerebral mucormycosis (ROCM) is used. The most common underlying illnesses of ROCM are diabetes mellitus, hematological malignancies, hematopoietic stem cell transplantation, and solid organ transplantation. Sporangiospores are deposited in the nasal turbinates and paranasal sinuses in immunocompromised patients. Qualitative and quantitative abnormalities of neutrophils, monocytes and macrophages increase the risk for development of mucormycosis. Altered iron metabolism also is a critical factor in the pathogenesis of patients with diabetes mellitus who are at risk for ROCM. Angioinvasion with thrombosis and tissue necrosis is a key pathophysiological feature of human Mucorales infection. The ethmoid sinus is a critical site from which sinus mucormycosis may extend through the lamina papyracea into the orbit, extraocular muscles, and optic nerve. The brain may be seeded by invasion of the ethmoidal and orbital veins, which drain into the cavernous sinuses. Diplopia and ophthalmoplegia may be the earliest manifestations of cavernous sinus syndrome before changes are apparent on diagnostic imaging modalities. Negative diagnostic imaging does not exclude cavernous sinus mucormycosis. Mucormycosis of the maxillary sinus has a constellation of clinical features that are different from that of ethmoid sinus mucormycosis. A painful black necrotic ulceration may develop on the hard palate, indicating extension from the maxillary sinus into the oral cavity. Orbital apex syndrome is an ominous complication of mucormycosis of the orbit. Once within the orbital compartment, organisms may extend posteriorly to the optic foramen, where the ophthalmic artery, ophthalmic nerve and optic nerve are threatened by invasion, edema, inflammation and necrosis. Early diagnosis of sinus mucormycosis is critical for prevention of extension to orbital and cerebral tissues. Optimal therapy requires a multidisciplinary approach that relies on prompt institution of appropriate antifungal therapy with amphotericin B, reversal of underlying predisposing conditions, and, where possible, surgical debridement of devitalized tissue. Outcomes are highly dependent upon the degree of immunosuppression, site and extent of infection, timeliness of therapy, and type of treatment provided. New modalities for early diagnosis and therapeutic intervention are critically needed for improved outcome of patients with ROCM. PMID:22684277

  2. Precise GPS orbits for geodesy

    NASA Technical Reports Server (NTRS)

    Colombo, Oscar L.

    1994-01-01

    The Global Positioning System (GPS) has become, in recent years, the main space-based system for surveying and navigation in many military, commercial, cadastral, mapping, and scientific applications. Better receivers, interferometric techniques (DGPS), and advances in post-processing methods have made possible to position fixed or moving receivers with sub-decimeter accuracies in a global reference frame. Improved methods for obtaining the orbits of the GPS satellites have played a major role in these achievements; this paper gives a personal view of the main developments in GPS orbit determination.

  3. Bending waves and orbital inclinations

    NASA Technical Reports Server (NTRS)

    Ward, William R.

    1991-01-01

    Disk tides may play an important role in the formation of a planetary system. Modification of protoplanet semi-major axes and eccentricities through density waves was suggested and calculations of linear and non-linear protoplanet-nebula interactions were carried out by a number of researchers. The possible significance of radial drift to the accretion process was discussed, while the evolution of orbital eccentricities was studied for a perturber orbiting external to a ring and for a perturber embedded in the ring. The possible importance of bending waves to the early evolution of protoplanet inclinations is described.

  4. Orbital dynamics in galaxy mergers

    NASA Astrophysics Data System (ADS)

    Hoffman, Loren

    In the favored vacuum energy + cold dark matter (ACDM) cosmology, galaxies form through a hierarchical merging process. Mergers between comparable-mass sys tems are qualitatively different from the ongoing accretion of small objects by much larger ones, in that they can radically transform the nature of the merging objects, e.g. through violent relaxation of the stars and dark matter, triggered starbursts, and quasar activity. This thesis covers two phenomena unique to major galaxy mergers: the formation of supermassive black hole (SMBH) binary and triple systems, and the transformation of the stellar orbit structure through violent relaxation, triggered gas inflow, and star formation. In a major merger, the SMBHs can spiral in and form a bound binary in less than a Hubble time. If the binary lifetime exceeds the typical time between mergers, then triple black hole (BH) systems may form. We study the statistics of close triple-SMBH encounters in galactic nuclei by computing a series of three-body orbits with physically-motivated initial conditions appropriate for giant elliptical galaxies. Our simulations include a smooth background potential consisting of a stellar bulge plus a dark matter halo, drag forces due to gravitational radiation and dynamical friction on the stars and dark matter, and a simple model of the time evolution of the inner density profile under heating and mass ejection by the SMBHs. We find that the binary pair coalesces as a result of repeated close encounters in ~85% of our runs. In about 40% of the runs the lightest BH is left wandering through the galactic halo or escapes the galaxy altogether. The triple systems typically scour out cores with mass deficits ~1-2 times their total mass. The high coalescence rate and prevalence of very high-eccentricity orbits could provide interesting signals for the future Laser Interferometer Space Antenna (LISA). Our study of remnant orbit structure involved 42 disk-disk mergers at various gas fractions, and 10 re-mergers of the 40% gas remnants. All simulations were run using a version of GADGET-2 [173] that included subresolution models of radiative cooling, star formation, and supernova and AGN feedback. The potential was frozen at the last snapshot of each simulation and the orbits of ~50,000 randomly chosen stars were integrated for ~100 dynamical times, and classified based on their Fourier spectra using the algorithm of [30]. The 40% gas remnants were found to be dominated by minor-axis tube orbits in their inner regions, whereas box orbits were the dominant orbit family in the inner parts of the dissipationless disk-disk and remnant-remnant systems. The phase space available to minor-axis tube orbits in even the 5% gas remnants was much larger than that in the dissipationless remnants, but the 5% gas remnants are not fast rotators because these orbits tend to be isotropically distributed at low gas fractions. Some of the remnants show significant minor axis rotation, due to large orientation twists in their outer parts (in the 40% gas remnants) and asymmetrically rotating major-axis tube orbits throughout the remnants (in the re-mergers).

  5. Biomaterials for orbital fractures repair

    PubMed Central

    Totir, M; Ciuluvica, R; Dinu, I; Careba, I; Gradinaru, S

    2015-01-01

    The unique and complex anatomy of the orbit requires significant contouring of the implants to restore the proper anatomy. Fractures of the orbital region have an incidence of 10-25% from the total facial fractures and the most common age group was the third decade of life. The majority of cases required reconstruction of the orbital floor to support the globe position and restore the shape of the orbit. The reason for this was that the bony walls were comminuted and/ or bone fragments were missing. Therefore, the reconstruction of the missing bone was important rather than reducing the bone fragments. This could be accomplished by using various materials. There is hardly any anatomic region in the human body that is so controversial in terms of appropriate material used for fracture repair: non resorbable versus resorbable, autogenous/ allogeneic/ xenogenous versus alloplastic material, non-prebent versus preformed (anatomical) plates, standard versus custom-made plates, nonporous versus porous material, non-coated versus coated plates. Thus, the importance of the material used for reconstruction becomes more challenging for the ophthalmologist and the oral and maxillofacial surgeon. PMID:25914737

  6. A Mars orbiter mission design

    NASA Astrophysics Data System (ADS)

    Castronuovo, Marco M.

    1992-08-01

    A preliminary study of a new orbiter mission to Mars using an earth gravity assist is presented. The trajectory resulting from this study has been evaluated utilizing Everhart's (1985) integrator RADAU. The mission sequences are described and compared to other proposed mission designs and some mission opportunities for the years 1997 to 2014 are discussed.

  7. Orbits in Strongly Curved Spacetime

    NSDL National Science Digital Library

    Walker, John

    This applet shows from three different physical perspectives the orbit of a low-mass test particle around a non-rotating black hole. Below the applet is an instructional guide to the applet and a description of the parameters involved.

  8. Orbit Determination in Satellite Geodesy

    Microsoft Academic Search

    G. Beutler; U. Hugentobler; T. Schildknecht

    2002-01-01

    For centuries orbit determination in Celestial Mechanics was a synonym for the determination of the six Keplerian elements of a minor planet or a comet in the solar system based on a short time series of (three or more) astrometric places observed from one or more observatories on the Earth surface. With the advent of the space age the problem

  9. Gauge Freedom in Orbital Mechanics

    Microsoft Academic Search

    Michael Efroimsky

    2005-01-01

    In orbital and attitude dynamics the coordinates and the Euler angles are expressed as functions of the time and six constants called elements. Under disturbance, the constants are endowed with time dependence. The Lagrange constraint is then imposed to guarantee that the functional dependence of the perturbed velocity on the time and constants stays the same as in the undisturbed

  10. Augmented orbiter heat rejection study

    NASA Technical Reports Server (NTRS)

    Hixon, C. W.

    1981-01-01

    Spacecraft radiator concepts are presented that relieve attitude restrictions required by the shuttle orbiter space radiator for baseline and extended capability STS missions. Cost effective heat rejection kits are considered which add additional capability in the form of attached spacelab radiators or a deployable radiator module.

  11. Viking orbiter stereo imaging catalog

    NASA Technical Reports Server (NTRS)

    Blasius, K. R.; Vertrone, A. V.; Lewis, B. H.; Martin, M. D.

    1982-01-01

    The extremely long mission of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of these photos can be used to form stereo images allowing the student of Mars to examine a subject in three dimensional. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set.

  12. NASA Facts, Orbits and Revolutions.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Washington, DC.

    This pamphlet is intended for senior high physics students. It contains information on the sidereal and synodic periods of revolution of an orbiting satellite, including their calculation. This pamphlet is one of the NASA Facts Science Series (each of which consists of four pages) and is designed to fit in the standard size three-ring notebook.…

  13. Precision orbit computations for Starlette

    NASA Technical Reports Server (NTRS)

    Marsh, J. G.; Williamson, R. G.

    1976-01-01

    The Starlette satellite, launched in February 1975 by the French Centre National d'Etudes Spatiales, was designed to minimize the effects of nongravitational forces and to obtain the highest possible accuracy for laser range measurements. Analyses of the first four months of global laser tracking data confirmed the stability of the orbit and the precision to which the satellite's position is established.

  14. Orbital abscess from an odontogenic infection.

    PubMed

    Kim, Il-Kyu; Kim, Ju-Rok; Jang, Keum-Soo; Moon, Yeon-Sung; Park, Sun-Won

    2007-01-01

    An orbital abscess is a rare but serious complication of an odontogenic infection, which can lead to loss of vision or worse. This paper presents a case of orbital abscess secondary to an infection from the upper molar teeth, which extended to the retobulbar and posterosuperior region of the orbit, close to the superior orbital fissure. The infection spreaded to the pterygopalatine and infratemporal fossa and then to the orbit via the inferior orbital fissure. This paper reviews the clinical presentation, differential diagnosis, route of spread, value of serial CT scanning, treatment and possible complications. PMID:17178478

  15. Orbital Debris Research at NASA

    NASA Technical Reports Server (NTRS)

    Stansbery, Eugene G.

    2009-01-01

    The United States has one of the most active programs of research of the orbital debris environment in the world. Much of the research is conducted by NASA s Orbital Debris Program Office at the Johnson Space Center. Past work by NASA has led to the development of national space policy which seeks to limit the growth of the debris population and limit the risk to spacecraft and humans in space and on the Earth from debris. NASA has also been instrumental in developing consistent international policies and standards. Much of NASA's efforts have been to measure and characterize the orbital debris population. The U.S. Department of Defense tracks and catalogs spacecraft and large debris with it's Space Surveillance Network while NASA concentrates on research on smaller debris. In low Earth orbit, NASA has utilized short wavelength radars such as Haystack, HAX, and Goldstone to statistically characterize the population in number, size, altitude, and inclination. For higher orbits, optical telescopes have been used. Much effort has gone into the understanding and removal of observational biases from both types of measurements. NASA is also striving to understand the material composition and shape characteristics of debris to assess these effects on the risk to operational spacecraft. All of these measurements along with data from ground tests provide the basis for near- and long-term modeling of the environment. NASA also develops tools used by spacecraft builders and operators to evaluate spacecraft and mission designs to assess compliance with debris standards and policies which limit the growth of the debris environment.

  16. Aiming at a 1-cm Orbit for Low Earth Orbiters: Reduced-Dynamic and Kinematic Precise Orbit Determination

    Microsoft Academic Search

    P. N. A. M. Visser; J. Van Den Ijssel

    2003-01-01

    The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP,\\u000a GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at\\u000a the few cm level. Such a level of accuracy might be achieved with the techniques of reduced-dynamic and kinematic precise\\u000a orbit

  17. Orbits and Interiors of Planets

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin

    2012-05-01

    The focus of this thesis is a collection of problems of timely interest in orbital dynamics and interior structure of planetary bodies. The first three chapters are dedicated to understanding the interior structure of close-in, gaseous extrasolar planets (hot Jupiters). In order to resolve a long-standing problem of anomalously large hot Jupiter radii, we proposed a novel magnetohydrodynamic mechanism responsible for inflation. The mechanism relies on the electro-magnetic interactions between fast atmospheric flows and the planetary magnetic field in a thermally ionized atmosphere, to induce electrical currents that flow throughout the planet. The resulting Ohmic dissipation acts to maintain the interior entropies, and by extension the radii of hot Jupiters at an enhanced level. Using self-consistent calculations of thermal evolution of hot Jupiters under Ohmic dissipation, we demonstrated a clear tendency towards inflated radii for effective temperatures that give rise to significant ionization of K and Na in the atmosphere, a trend fully consistent with the observational data. Furthermore, we found that in absence of massive cores, low-mass hot Jupiters can over-flow their Roche-lobes and evaporate on Gyr time-scales, possibly leaving behind small rocky cores. Chapters four through six focus on the improvement and implications of a model for orbital evolution of the solar system, driven by dynamical instability (termed the "Nice" model). Hydrodynamical studies of the orbital evolution of planets embedded in protoplanetary disks suggest that giant planets have a tendency to assemble into multi-resonant configurations. Following this argument, we used analytical methods as well as self-consistent numerical N-body simulations to identify fully-resonant primordial states of the outer solar system, whose dynamical evolutions give rise to orbital architectures that resemble the current solar system. We found a total of only eight such initial conditions, providing independent constraints for the solar system's birth environment. Next, we addressed a significant drawback of the original Nice model, namely its inability to create the physically unique, cold classical population of the Kuiper Belt. Specifically, we showed that a locally-formed cold belt can survive the transient instability, and its relatively calm dynamical structure can be reproduced. The last four chapters of this thesis address various aspects and consequences of dynamical relaxation of planetary orbits through dissipative effects as well as the formation of planets in binary stellar systems. Using octopole-order secular perturbation theory, we demonstrated that in multi-planet systems, tidal dissipation often drives orbits onto dynamical "fixed points," characterized by apsidal alignment and lack of periodic variations in eccentricities. We applied this formalism towards investigating the possibility that the large orbital eccentricity of the transiting Neptune-mass planet Gliese 436b is maintained in the face of tidal dissipation by a second planet in the system and computed a locus of possible orbits for the putative perturber. Following up along similar lines, we used various permutations of secular theory to show that when applied specifically to close-in low-mass planetary systems, various terms in the perturbation equations become separable, and the true masses of the planets can be solved for algebraically. In practice, this means that precise knowledge of the system's orbital state can resolve the sin( i) degeneracy inherent to non-transiting planets. Subsequently, we investigated the onset of chaotic motion in dissipative planetary systems. We worked in the context of classical secular perturbation theory, and showed that planetary systems approach chaos via the so-called period-doubling route. Furthermore, we demonstrated that chaotic strange attractors can exist in mildly damped systems, such as photo-evaporating nebulae that host multiple planets. Finally, we considered planetary formation in highly inclined binary systems,

  18. Overview of the Mars Reconnaissance Orbiter mission

    NASA Technical Reports Server (NTRS)

    Mateer, B.; Graf, J.; Zurek, R.; Jones, R.; Eisen, H.; Johnston, M.; Jai, D. B.

    2002-01-01

    The Mars Reconnaissance Orbiter will deliver to Mars orbit a payload to conduct remote sensing science observations, characterize sites for future landers, and provide critical telecom/navigation relay capability for follow-on missions.

  19. Orbiter Kapton wire operational requirements and experience

    NASA Technical Reports Server (NTRS)

    Peterson, R. V.

    1994-01-01

    The agenda of this presentation includes the Orbiter wire selection requirements, the Orbiter wire usage, fabrication and test requirements, typical wiring installations, Kapton wire experience, NASA Kapton wire testing, summary, and backup data.

  20. MOOSE: Manned On-Orbit Servicing Equipment

    NASA Technical Reports Server (NTRS)

    Budinoff, J. (editor); Leontsinis, N. (editor); Lane, J. (editor); Singh, R. (editor); Angelone, K.; Boswell, C.; Chamberlain, I.; Concha, M.; Corrodo, M.; Custodio, O.

    1993-01-01

    The ability to service satellites has thus far been limited to low earth orbit platforms within reach of the Space Shuttle. Other orbits, such as geosynchronous orbits containing high-value spacecraft have not been attainable by a servicing vehicle. The useful life of a satellite can be extended by replacing spent propellant and damaged orbital replacement units, forestalling the need for eventual replacement. This growing need for satellite on-orbits servicing can be met by the Manned On-Orbit Servicing Equipment (MOOSE). Missions requiring orbit transfer capability, precision manipulation and maneuvering, and man-in-the-loop control can be accomplished using MOOSE. MOOSE is a flexible, reusable, single operator, aerobraking spacecraft designed to refuel, repair, and service orbiting spacecraft. MOOSE will be deployed from Space Station Freedom, (SSF), where it will be stored, resupplied, and refurbished.

  1. Management of ocular, orbital, and adnexal trauma

    SciTech Connect

    Spoor, T.C.; Nesi, F.A.

    1988-01-01

    This book contains 20 chapters. Some of the chapter titles are: The Ruptured Globe: Primary Care; Corneal Trauma, Endophthalmitis; Antibiotic Usage; Radiology of Orbital Trauma; Maxillofacial Fractures; Orbital Infections; and Basic Management of Soft Tissue Injury.

  2. Orbital evolution around irregular bodies

    NASA Astrophysics Data System (ADS)

    Rossi, A.; Marzari, F.; Farinella, P.

    1999-11-01

    The new profiles of the space missions aimed at asteroids and comets, moving from fly-bys to rendezvous and orbiting, call for new spaceflight dynamics tools capable of propagating orbits in an accurate way around these small irregular objects. Moreover, interesting celestial mechanics and planetary science problems, requiring the same sophisticated tools, have been raised by the first images of asteroids (Ida/Dactyl, Gaspra and Mathilde) taken by the Galileo and NEAR probes, and by the discovery that several near-Earth asteroids are probably binary. We have now developed two independent codes which can integrate numerically the orbits of test particles around irregularly shaped primary bodies. One is based on a representation of the central body in terms of "mascons" (discrete spherical masses), while the other one models the central body as a polyhedron with a variable number of triangular faces. To check the reliability and performances of these two codes we have performed a series of tests and compared their results. First we have used the two algorithms to calculate the gravitational potential around non-spherical bodies, and have checked that the results are similar to each other and to those of other, more common, approaches; the polyhedron model appears to be somewhat more accurate in representing the potential very close to the body's surface. Then we have run a series of orbit propagation tests, integrating several different trajectories of a test particle around a sample ellipsoid. Again the two codes give results in fair agreement with each other. By comparing these numerical results to those predicted by classical perturbation formulae, we have noted that when the orbit of the test particle gets close to the surface of the primary, the analytical approximations break down and the corresponding predictions do not match the results of the numerical integrations. This is confirmed by the fact that the agreement gets better and better for orbits farther away from the primary. Finally, we have found that in terms of CPU time requirements, the performances of the two codes are quite similar, and that the optimal choice probably depends on the specific problem under study.

  3. An analysis of thrust of a realistic solar sail with focus on a flight validation mission in a geocentric orbit

    NASA Astrophysics Data System (ADS)

    Campbell, Bruce A.

    Several scientifically important space flight missions have been identified that, at this time, can only be practically achieved using a solar sail propulsion system. These missions take advantage of the potentially continuous force on the sail, provided by solar radiation, to produce significant changes in the spacecraft's velocity, in both magnitude and/or direction, without the need for carrying the enormous amount of fuel that conventional propulsion systems would require to provide the same performance. However, to provide thrust levels that would support these missions requires solar sail areas in the (tens of) thousands of square meter sizes. To realize this, many technical areas must be developed further and demonstrated in space before solar sails will be accepted as a viable space mission propulsion system. One of these areas concerns understanding the propulsion performance of a realistic solar sail well enough for mission planning. Without this understanding, solar sail orbits could not be predicted well enough to meet defined mission requirements, such as rendezvous or station-keeping, and solar sail orbit optimization, such as minimizing flight time, could be close to impossible. In most mission studies, either an "ideal" sail's performance is used for mission planning, or some top-level assumptions of certain nonideal sail characteristics are incorporated to give a slightly better estimate of the sail performance. This paper identifies the major sources of solar sail thrust performance uncertainty, and analyzes the most significant ones to provide a more comprehensive understanding of thrust generation by a "realistic" solar sail. With this understanding, mission planners will be able to more confidently and accurately estimate the capabilities of such a system. The first solar sail mission will likely be a system validation mission, using a relatively small sail in a geocentric (Earth-centered) orbit. The author has been involved in conceptual design of such missions, and through this became aware of the current status in solar sail system development, and the need for a better understanding of the thrust performance of a "realistic" solar sail. Such a validation mission is significantly different than most of the "operational" science missions envisioned to utilize a solar sail propulsion system. These future missions will likely use very large, very light sails in heliocentric orbits far away from major gravity fields like planets, have very long mission lifetimes (years), and will conduct relatively minor and slow orbital and attitude control maneuvers. Nonetheless, most of the capabilities of later systems can be gleaned from a small geocentric validation mission. This paper is a significant step toward understanding the thrust characteristics and performance of a realistic solar sail, and provides insight to the methods by which this understanding can be corroborated by a solar sail validation mission.

  4. The origin of Pluto's peculiar orbit

    Microsoft Academic Search

    Renu Malhotra

    1993-01-01

    THE origin of Pluto's unusual orbit---the most eccentric and inclined of all the planets---remains a mystery. The orbits of Pluto and Neptune overlap, but close approaches of these two planets are prevented by the existence of a resonance condition1: Pluto's orbital period is exactly 3\\/2 that of Neptune, which ensures that the conjunctions always occur near Pluto's aphelion. Long-term orbit

  5. An Analytical Satellite Orbit Predictor (ASOP)

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The documentation and user's guide are presented for the analytical satellite orbit predictor computer program which is intended to be used for computation of near-earth orbits including those of the shuttle orbiter and its payloads. The Poincare-Similar elements used make it possible to compute near-earth orbits to within an accuracy of a few meters. Recursive equations are used instead of complicated formulas. Execution time is on the order of a few milliseconds.

  6. The geostationary orbit and developing countries

    NASA Technical Reports Server (NTRS)

    Medina, E. R.

    1982-01-01

    The geostationary orbit is becoming congested due to use by several countries throughout the world, and the request for use of this orbit is increasing. There are 188 geostationary stations in operation. An equitable distribution of stations on this orbit is requested.

  7. Orbital Actinomycosis Associated with Painful Ophthalmoplegia

    Microsoft Academic Search

    Livio Pagliani; Luca Campi; Gian Maria Cavallini

    2006-01-01

    Purpose: To evaluate a case of orbital actinomycosis presenting as Tolosa-Hunt syndrome in a patient with a history of carcinomas of the kidney and breast. Methods: A woman with ingravescent painful ophthalmoplegia was brought to our observation. Brain and orbital and total body CT scans showed the presence of two orbital neoformations and a miliary pattern of dissemination in the

  8. Scientific Research in the Lunar Orbiting Mission

    Microsoft Academic Search

    S. Sasaki; Y. Iijima; K. Tanaka; M. Kato; M. Hashimoto; H. Mizutani; Y. Takizawa

    2002-01-01

    and technology development. The launch was rescheduled last summer in the rearrangement of HII-A launch schedule. The main objective of the mission is to study the origin and evolution of the Moon. The spacecraft consists of a main orbiter at about 100 km altitude in the polar circular orbit and two subsatellites in the elliptical orbits with the apolune at

  9. NASA's Lunar Reconnaissance Orbiter Cameras (LROC)

    Microsoft Academic Search

    M. Robinson; A. McEwen; E. Eliason; B. Joliff; H. Hiesinger; M. Malin; P. Thomas; E. Turtle; S. Brylow

    2006-01-01

    The Lunar Reconnaissance Orbiter LRO mission is scheduled to launch in the fall of 2008 as part of NASA s Robotic Lunar Exploration Program and is the first spacecraft to be built as part of NASA s Vision for Space Exploration The orbiter will be equipped with seven scientific instrument packages one of which is LROC The Lunar Reconnaissance Orbiter

  10. TDRS orbit determination by radio interferometry

    Microsoft Academic Search

    Michael S. Pavloff

    1994-01-01

    In support of a NASA study on the application of radio interferometry to satellite orbit determination, MITRE developed a simulation tool for assessing interferometry tracking accuracy. The Orbit Determination Accuracy Estimator (ODAE) models the general batch maximum likelihood orbit determination algorithms of the Goddard Trajectory Determination System (GTDS) with the group and phase delay measurements from radio interferometry. ODAE models

  11. Outgassing products from orbiter TPS materials

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.; Lash, Tom J.; Rawls, J. Richard

    1995-01-01

    The Space Transportation System (STS) orbiters are known to be significant sources of outgassing in low earth orbit (LEO). Infrared and mass spectra of residues and outgassing from orbiter thermal protection tile and an external blanket are presented. Several sources of methyl and phenyl methyl silicones are identified. About fifty pounds of silicones are estimated to be outgassed during an STS mission.

  12. Transfer orbit stage (TOS) guidance and control

    Microsoft Academic Search

    James R. Stuart; Marshall H. Kaplan; Randall E. Coffey; Thomas W. White

    1986-01-01

    This paper describes the strap-down, ring laser gyro-based guidance and control system of the current Transfer Orbit Stage (TOS) family of orbital transfer vehicles being developed by Orbital Sciences Corporation. The paper begins with a summary review of the key features and guidance and control approaches used by that employed by the TOS family of upper stages. The TOS system

  13. Prototyping a Planning System for Orbital Reconstruction

    E-print Network

    Bartz, Dirk

    . A malformed orbit causes one eye to be displaced from a position that is sym- metrical to the eyePrototyping a Planning System for Orbital Reconstruction Jan Fischer1 , Melissa Mekic1 , ´Angel del orbit to be symmetrical to the intact one. Here, the main difficulty of this intervention

  14. Orbit determination for ISRO satellite missions

    Microsoft Academic Search

    Ch. Sreehari Rao; S. K. Sinha

    1985-01-01

    Indian Space Research Organisation (ISRO) has been successful in using the in-house developed orbit determination and prediction software for satellite missions of Bhaskara, Rohini and APPLE. Considering the requirements of satellite missions, software packages are developed, tested and their accuracies are assessed. Orbit determination packages developed are SOIP, for low earth orbits of Bhaskara and Rohini missions, ORIGIN and ODPM,

  15. Simulation of Atomic and Molecular Orbitals

    ERIC Educational Resources Information Center

    Massey, A. G.; Massey S.

    1976-01-01

    Describes the use of magnets to simulate s, p, and d atomic orbitals from which a wide variety of molecular orbitals can be derived. The technique gives students an idea of molecular orbitals' shapes and stresses the importance of symmetry labels. (MLH)

  16. Current Status of Venus orbiter Akatsuki

    E-print Network

    Widemann, Thomas

    Current Status of Venus orbiter Akatsuki Takeshi Imamura (JAXA, Japan) and AKATSUKI Project Team #12;Venus orbiter Akatsuki ·! Science target : `Weather of Venus' ­! Mechanism of `super was launched in May 2010. The Venus orbit insertion scheduled for December 2010 has failed. Now Akatsuki

  17. Major orbital complications of endoscopic sinus surgery

    Microsoft Academic Search

    C Rene; G E Rose; R Lenthall; I Moseley

    2001-01-01

    BACKGROUNDThe paranasal sinuses are intimately related to the orbit and consequently sinus disease or surgery may cause severe orbital complications. Complications are rare but can result in serious morbidity, the most devastating of which is severe visual loss.METHODSA retrospective review was undertaken of four cases of severe orbital trauma during endoscopic sinus surgery.RESULTSAll the cases suffered medial rectus damage, one

  18. Tesseral resonance effects on satellite orbits

    Microsoft Academic Search

    G. S. Gedeon

    1969-01-01

    Resonance effects on satellite orbits due to tesseral harmonics in the potential field have been studied by many authors. Most of these studies have been restricted to nearly circular 24-hour orbits and to the deep resonance regime, where there is exact commensurability between earth rotation and orbit period. Resonance effects have also been noted, however, on eccentric synchronous and subsynchronous

  19. Localized correlation treatment using natural bond orbitals

    Microsoft Academic Search

    N. Flocke; Rodney J. Bartlett

    2003-01-01

    We present studies using natural bond orbitals (NBOs) as a starting point for a localized electron correlation treatment, as these kind of localized orbitals lead to CCSD results which show significant transferability and exponential decay patterns in the T?2 amplitudes. The NBO CCSD approach combines the advantages of both the HF CCSD formulation (less amplitudes, orthogonal orbitals) and the AO-based

  20. Design of a Multi-Moon Orbiter

    Microsoft Academic Search

    S. D. Ross; W. S. Koon; M. W. Lo; J. E. Marsden

    The Multi-Moon Orbiter concept is introduced, wherein a single spacecraft orbits several moons of Jupiter, allowing long duration observations. The V requirements for this mission can be low if ballistic captures and resonant gravity assists by Jupiter's moons are used. For example, using only 22 m\\/s, a spacecraft initially injected in a jovian orbit can be directed into a capture

  1. Geopotential resonances on Vanguard orbits

    NASA Technical Reports Server (NTRS)

    Wagner, C. A.

    1977-01-01

    Since their establishment in 1959 the orbits of Vanguard 3 (1959-7A) and the Vanguard 2 rocket (1959-2B) have been slowly contracting through at least five strong resonances of eleventh order. Tracking with Baker-Nunn cameras and the U.S. Navy space surveillance (radio interferometer) system over a 14-year period has revealed resonant fluctuations on them of up to 0.035 deg in inclination (peak to peak). Six geopotential terms (lumped coefficients) of eleventh order and three of twenty-second order have been measured by using orbit inclinations derived from this tracking record. The terms of eleventh order are significantly smaller than is predicted by Kaula's rule. (The lumped coefficients are sensitive to geopotential effects as high as thirty-seventh degree.) These observed terms are compatible with a recent 27-satellite geopotential solution (GEM 7) whose formal coefficent errors are increased by a factor of 3.3.

  2. Pursuit/evasion in orbit

    NASA Technical Reports Server (NTRS)

    Kelley, H. J.; Cliff, E. M.; Lutze, F. H.

    1981-01-01

    Maneuvers available to a spacecraft having sufficient propellant to escape an antisatellite satellite (ASAT) attack are examined. The ASAT and the evading spacecraft are regarded as being in circular orbits, and equations of motion are developed for the ASAT to commence a two-impulse maneuver sequence. The ASAT employs thrust impulses which yield a minimum-time-to-rendezvous, considering available fuel. Optimal evasion is shown to involve only in-plane maneuvers, and begins as soon as the ASAT launch information is gathered and thrust activation can be initiated. A closest approach, along with a maximum evasion by the target spacecraft, is calculated to be 14,400 ft. Further research to account for ASATs in parking orbit and for generalization of a continuous control-modeled differential game is indicated.

  3. Pursuit/evasion in orbit

    NASA Astrophysics Data System (ADS)

    Kelley, H. J.; Cliff, E. M.; Lutze, F. H.

    1981-09-01

    Maneuvers available to a spacecraft having sufficient propellant to escape an antisatellite satellite (ASAT) attack are examined. The ASAT and the evading spacecraft are regarded as being in circular orbits, and equations of motion are developed for the ASAT to commence a two-impulse maneuver sequence. The ASAT employs thrust impulses which yield a minimum-time-to-rendezvous, considering available fuel. Optimal evasion is shown to involve only in-plane maneuvers, and begins as soon as the ASAT launch information is gathered and thrust activation can be initiated. A closest approach, along with a maximum evasion by the target spacecraft, is calculated to be 14,400 ft. Further research to account for ASATs in parking orbit and for generalization of a continuous control-modeled differential game is indicated.

  4. Viking Orbiter: Views of Mars

    NSDL National Science Digital Library

    1980-05-09

    This website is an electronic version of an historical NASA (National Aeronautics and Space Administration) publication containing information about the Viking Orbiter and images it took of the planet Mars. This book incorporates images acquired by the Viking orbiters beginning in 1976. The pictures here represent only a small fraction of the many thousands taken, and were chosen to illustrate the diverse geology and atmospheric phenomena of Mars. General information about the Viking mission highlights the purpose of sending these two spacecraft to the planet Mars. The images contain descriptions and explanations of what is being shown and cover planetary features such as channels, Valles Marineris canyon, volcanic features and Olympus Mons, comparison between Earth and Mars, deformation, craters, the moons Phobos and Deimos, surface processes (wind, mass wasting), polar regions, planet color, atmosphere and the Viking 1 and Viking 2 landing sites.

  5. Environmental dynamics at orbital altitudes

    NASA Technical Reports Server (NTRS)

    Karr, G. R.

    1976-01-01

    The influence of real satellite aerodynamics on the determination of upper atmospheric density was investigated. A method of analysis of satellite drag data is presented which includes the effect of satellite lift and the variation in aerodynamic properties around the orbit. The studies indicate that satellite lift may be responsible for the observed orbit precession rather than a super rotation of the upper atmosphere. The influence of simplifying assumptions concerning the aerodynamics of objects in falling sphere analysis were evaluated and an improved method of analysis was developed. Wind tunnel data was used to develop more accurate drag coefficient relationships for studying altitudes between 80 and 120 Km. The improved drag coefficient relationships revealed a considerable error in previous falling sphere drag interpretation. These data were reanalyzed using the more accurate relationships. Theoretical investigations of the drag coefficient in the very low speed ratio region were also conducted.

  6. Orbital changes during hypersonic aerocruise

    NASA Technical Reports Server (NTRS)

    Mease, Kenneth D.; Vinh, Nguyen X.; Lee, Jaemyong

    1987-01-01

    A novel mathematical approach that allows the analysis of orbital changes occurring during an aerocruise maneuver to be conducted in two distinct stages is presented. In the first stage, the aerodynamic turn is determined using a nondimensional form of the equations of motion that is free of singularities, and the way in which speed, altitude, angle of attack, and thrust direction should be chosen to maximize the aerodynamic turn for a given propellant expenditure is demonstrated. In the second analysis stage, the aerodynamic turn is translated into changes in the orbital elements with respect to the equatorial plane; analytic solutions for the initial arguments of latitude that maximize the change in inclination and in the longitude of the ascending node are given. As the initial inclination decreases toward zero, the optimal location moves from the apex toward the node.

  7. On-orbit spacecraft reliability

    NASA Technical Reports Server (NTRS)

    Bloomquist, C.; Demars, D.; Graham, W.; Henmi, P.

    1978-01-01

    Operational and historic data for 350 spacecraft from 52 U.S. space programs were analyzed for on-orbit reliability. Failure rates estimates are made for on-orbit operation of spacecraft subsystems, components, and piece parts, as well as estimates of failure probability for the same elements during launch. Confidence intervals for both parameters are also given. The results indicate that: (1) the success of spacecraft operation is only slightly affected by most reported incidents of anomalous behavior; (2) the occurrence of the majority of anomalous incidents could have been prevented piror to launch; (3) no detrimental effect of spacecraft dormancy is evident; (4) cycled components in general are not demonstrably less reliable than uncycled components; and (5) application of product assurance elements is conductive to spacecraft success.

  8. Mars Orbiting Plasma Surveyor (MOPS)

    NASA Astrophysics Data System (ADS)

    Barabash, S.; Andre, M.; Blomberg, L. G.; Lundin, R.; Marklund, G. T.; Rathsman, P.; von Scheele, F.; Wahlund, J.-E.

    Mars Orbiting Plasma Surveyor (MOPS) S. Barabash (1), M. André (2), L. G. Blomberg (3), R. Lundin (1),G. T. Marklund (3), P. Rathsman (4), F. von Schéele (4), J.-E. Wahlund (2) (1) Swedish Institute of Space Physics, Kiruna, Sweden (stas@irf.se) (2) Swedish Institute of Space Physics, Uppsala, Sweden (3) Royal Institute of Technology, Department of Space and Plasma Physics , Stockholm, Sweden (4) Swedish Space Corporation, Solna, Sweden Mars Orbiting Plasma Surveyor (MOPS) is a microsatellite mission focused on studies of the near - Mars environment and the planet - solar wind interaction. The recent findings by the ESA Mars Express mission further highlighted the complexity of the processes taking place at the planet resulting from the solar wind interaction that strongly affect the planet's atmosphere. However, despite many previous Martian missions carrying different types of space plasma experiments, a comprehensive investigation including simultaneous measurements of particles, fields, and waves has never been performed. We propose a spinning spacecraft of a mass of 50-80 kg with a 10 kg payload which can "hitchhike" on another platform until Mars orbit insertion and then be released into a suitable orbit. The spacecraft design is based on the experience gained in very successful Swedish space plasma missions, Viking, Freja, Astrid -1, and Astrid - 2. In the present mission design, the MOPS spacecraft is equipped with its own 1m high gain antenna for direct communication with the Earth. The payload includes a wave experiment with wire booms, magnetometer with a rigid boom, electron and ion energy spectrometers and an ion mass analyser. An energetic neutral atom imager and an UV photometer may complete the core payload.

  9. Assembling the Skylab Orbital Workshop

    NASA Technical Reports Server (NTRS)

    1970-01-01

    This photograph was taken during assembly of the bottom and upper floors of the Skylab Orbital Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment.

  10. Ancient schwannoma of the orbit.

    PubMed

    Kulkarni, Anjali S; Anjum, Shaziya; Kokandakar, Hemant R; Bindu, Rajan S; Awargaonkar, Amarnath

    2014-05-01

    The ancient schwannoma is a rare variant of a neurilemoma with a course typical of a slow-growing benign neoplasm. Histologically, it can be confused with a malignant mesenchymal tumor because of increased cellularity, nuclear pleomorphism, and hyperchromatism. Despite the degree of nuclear atypia, mitotic figures are absent. We describe the clinical and histopathologic features of an ancient schwannoma of the orbit. A need for early removal of such tumors is recommended to prevent complications. PMID:25136229

  11. Ancient schwannoma of the orbit

    PubMed Central

    Kulkarni, Anjali S.; Anjum, Shaziya; Kokandakar, Hemant R.; Bindu, Rajan S.; Awargaonkar, Amarnath

    2014-01-01

    The ancient schwannoma is a rare variant of a neurilemoma with a course typical of a slow-growing benign neoplasm. Histologically, it can be confused with a malignant mesenchymal tumor because of increased cellularity, nuclear pleomorphism, and hyperchromatism. Despite the degree of nuclear atypia, mitotic figures are absent. We describe the clinical and histopathologic features of an ancient schwannoma of the orbit. A need for early removal of such tumors is recommended to prevent complications. PMID:25136229

  12. Geological exploration from orbital altitudes

    USGS Publications Warehouse

    Badgley, Peter C.; Fischer, William A.; Lyon, Ronald J. P.

    1965-01-01

    The National Aeronautics & Space Administration is planning geologic exploration from orbiting spacecraft. For that purpose it is evaluating new and refined exploration tools, often called remote sensors, including devices that are sensitive to force fields, such as gravity gradient systems, and devices that record the reflection or emission of electromagnetic energy. Both passive electromagnetic sensors (those that rely on natural sources of illumination, such as the Sun) and active electromagnetic sensors (which use an artificial source of illumination) are being considered.

  13. Ionospheric Imaging from Geostationary Orbit

    Microsoft Academic Search

    R. P. McCoy; K. S. Wood; K. F. Dymond; S. E. Thonnard

    2001-01-01

    An ultraviolet imager is under development to image the ionosphere and thermosphere from geostationary orbit. The instrument will consist of two telescopes, one with a filter wheel to measure the atomic oxygen airglow emission at 130.4 nm and 135.6 nm and molecular nitrogen Lyman-Birge-Hopfield bands near 142.5 nm. The second telescope will image the atomic oxygen ion resonance multiplet at

  14. Vigilance problems in orbiter processing

    NASA Technical Reports Server (NTRS)

    Swart, William W.; Safford, Robert R.; Kennedy, David B.; Yadi, Bert A.; Barth, Timothy S.

    1993-01-01

    A pilot experiment was done to determine what factors influence potential performance errors related to vigilance in Orbiter processing activities. The selected activities include post flight inspection for burned gap filler material and pre-rollout inspection for tile processing shim material. It was determined that the primary factors related to performance decrement were the color of the target and the difficulty of the target presentation.

  15. Introduction to Orbital Sciences Corporation

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A general overview of the Orbital Sciences Corporation (OSC) is presented. The following topics are covered: (1) manpower, facilities, and financial growth; (2) organization and management team; (3) the Space Data Division organization; (4) the Chandler facility; (5) Space Data-Products and Services; (6) space transportation systems; (7) spacecraft and space support systems; (8) turn-key suborbital launch services and support systems; and (9) OSC suborbital booster performance.

  16. Periodic Orbits in a Mechanical System with Strongly Coupled Spin and Orbital Motions

    Microsoft Academic Search

    Keith Hagenbuch

    1996-01-01

    An ideal superball bouncing on a rigid surface is an interesting and tractible example of a mechanical system in which 'orbital' and 'spin' angular momenta are strongly coupled. Unlike weakly coupled planetary orbits that are planar, strongly coupled orbits are non-planar and quite complex. In particular, orbits of such a ball inside a sphere, while having a certain symmetry in

  17. Analysis of parking orbits for a STS external tank in low Earth orbit

    Microsoft Academic Search

    James E. Cross

    1990-01-01

    A study was conducted of a single external tank in low earth orbit. Criteria for a parking orbit are then defined. Various orbits are then selected by varying the semi-major axis, eccentricity, and inclination. The resulting equations of motion for each of the above orbits (including atmospheric drag and a 2x0 gravity model) are numerically integrated over a time span

  18. Normal form invariants around spin--orbit periodic orbits Alessandra Celletti and Corrado Falcolini

    E-print Network

    system (including the Moon) are trapped in a syn­ chronous spin--orbit resonance, namely T rev =T rot = 1Normal form invariants around spin--orbit periodic orbits Alessandra Celletti and Corrado Falcolini (Italy) May 31, 2000 Abstract. We consider a model of spin--orbit interaction, describing the motion

  19. Mars Orbiting Plasma Surveyor (MOPS)

    NASA Astrophysics Data System (ADS)

    Barabash, S.; André, M.; Blomberg, L. G.; Lundin, R.; Marklund, G. T.; Rathsman, P.; von Schuele, F.; Wahlund, J.-E.

    Mars Orbiting Plasma Surveyor MOPS is a microsatellite mission focused on studies of the near - Mars environment and the planet - solar wind interaction The recent findings by the ESA Mars Express mission further highlighted the complexity of the processes taking place at the planet resulting from the solar wind interaction that strongly affect the planet s atmosphere However despite many previous Martian missions carrying different types of space plasma experiments a comprehensive investigation including simultaneous measurements of particles fields and waves has never been performed We propose a spinning spacecraft of a mass of 50-80 kg with a 10 kg payload which can hitchhike on another platform until Mars orbit insertion and then be released into a suitable orbit The spacecraft design is based on the experience gained in very successful Swedish space plasma missions Viking Freja Astrid -1 and Astrid - 2 In the present mission design the MOPS spacecraft is equipped with its own 1m high gain antenna for direct communication with the Earth The payload includes a wave experiment with wire booms magnetometer with a rigid boom electron and ion energy spectrometers and an ion mass analyser An energetic neutral atom imager and an UV photometer may complete the core payload

  20. Synchronous orbit power technology needs

    NASA Technical Reports Server (NTRS)

    Slifer, L. W., Jr.; Billerbeck, W. J.

    1979-01-01

    The needs are defined for future geosynchronous orbit spacecraft power subsystem components, including power generation, energy storage, and power processing. A review of the rapid expansion of the satellite communications field provides a basis for projection into the future. Three projected models, a mission model, an orbit transfer vehicle model, and a mass model for power subsystem components are used to define power requirements and mass limitations for future spacecraft. Based upon these three models, the power subsystems for a 10 kw, 10 year life, dedicated spacecraft and for a 20 kw, 20 year life, multi-mission platform are analyzed in further detail to establish power density requirements for the generation, storage and processing components of power subsystems as related to orbit transfer vehicle capabilities. Comparison of these requirements to state of the art design values shows that major improvements, by a factor of 2 or more, are needed to accomplish the near term missions. However, with the advent of large transfer vehicles, these requirements are significantly reduced, leaving the long lifetime requirement, associated with reliability and/or refurbishment, as the primary development need. A few technology advances, currently under development, are noted with regard to their impacts on future capability.

  1. Orbits of nine Uranian rings

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; French, R. G.; Frogel, J. A.; Elias, J. H.; Mink, D. J.; Liller, W.

    1981-01-01

    Observations of a stellar occultation by Uranus and its nine rings are presented and used to examine the structures and kinematics of the rings. The observations of the occultation of the K giant star KM 12 were obtained in the K band with the 4-m CTIO telescope at a signal-to-noise ratio higher than any previously obtained. Ring occultation profiles reveal the alpha ring to possibly have a double structure and less abrupt boundaries than the gamma ring, which exhibits diffraction fringes, while the eta ring is a broad ring with an unresolved narrow component at its inner edge. The present timing data, as well as previous occultation timings, are fit to a kinematic model in which all nine rings are treated as coplanar eclipses of zero inclination, precessing due to the zonal harmonics of the Uranian gravitational potential to obtain solutions for the ring orbits. Analysis of the residuals from the fitted orbits reveals that the proposed model is a good representation of ring kinematics. The reference system defined by the orbit solutions has also been used to obtain a value of 0.022 + or - 0.003 for the ellipticity of Uranus and a Uranian rotation period of 15.5 h.

  2. Density-orbital embedding theory

    SciTech Connect

    Gritsenko, O. V.; Visscher, L. [Section Theoretical Chemistry, VU University, De Boelelaan 1083, NL-1081 HV Amsterdam (Netherlands) and Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2010-09-15

    In the article density-orbital embedding (DOE) theory is proposed. DOE is based on the concept of density orbital (DO), which is a generalization of the square root of the density for real functions and fractional electron numbers. The basic feature of DOE is the representation of the total supermolecular density {rho}{sub s} as the square of the sum of the DO {phi}{sub a}, which represents the active subsystem A and the square root of the frozen density {rho}{sub f} of the environment F. The correct {rho}{sub s} is obtained with {phi}{sub a} being negative in the regions in which {rho}{sub f} might exceed {rho}{sub s}. This makes it possible to obtain the correct {rho}{sub s} with a broad range of the input frozen densities {rho}{sub f} so that DOE resolves the problem of the frozen-density admissibility of the current frozen-density embedding theory. The DOE Euler equation for the DO {phi}{sub a} is derived with the characteristic embedding potential representing the effect of the environment. The DO square {phi}{sub a}{sup 2} is determined from the orbitals of the effective Kohn-Sham (KS) system. Self-consistent solution of the corresponding one-electron KS equations yields not only {phi}{sub a}{sup 2}, but also the DO {phi}{sub a} itself.

  3. Extended Duration Orbiter Medical Project

    NASA Technical Reports Server (NTRS)

    Leach, C. S.; Pool, S. L.; Sawin, C. F.; Nicogossian, A. E.

    1990-01-01

    The Extended Duration Orbiter (EDO) program addresses a need for more time to perform experiments and other tasks during Space Shuttle missions. As a part of this program, the Extended Duration Orbiter Medical Project (EDOMP) has been instituted to obtain information about physiologic effects of extending mission duration and the effectiveness of countermeasures against factors that might compromise crew health, safety, or performance on extended-duration missions. Only those investigations that address and characterize operational problems, develop countermeasures, or evaluate the effectiveness of countermeasures will be pursued. The EDOMP investigations will include flight-associated Detailed Supplementary Objectives as well as ground-based studies simulating the influence of microgravity. Investigator teams have been formed in the following areas: biomedical physiology, cardiovascular and fluid/electrolyte physiology, environmental health, muscle and exercise physiology, and neurophysiology. Major operational questions must be answered in each of these areas, and investigations have been designed to answer them. The EDO program will proceed only after countermeasures have been shown to be effective in preventing or mitigating the adverse changes they have been designed to attenuate. The program is underway and will continue on each Shuttle flight as the manifest builds toward a 16-day orbital flight.

  4. Fitting orbits to tidal streams

    NASA Astrophysics Data System (ADS)

    Binney, James

    2008-05-01

    Recent years have seen the discovery of many tidal streams through the Galaxy. Relatively straightforward observations of a stream allow one to deduce three phase-space coordinates of an orbit. An algorithm is presented that reconstructs the missing phase-space coordinates from these data. The reconstruction starts from assumed values of the Galactic potential and a distance to one point on the orbit, but with noise-free data the condition that energy be conserved on the orbit enables one to reject incorrect assumptions. The performance of the algorithm is investigated when errors are added to the input data that are comparable to those in published data for the streams of Pal 5. It is found that the algorithm returns distances and proper motions that are accurate to of the order of 1 per cent, and enables one to reject quite resonable but incorrect trial potentials. In practical applications, it will be important to minimize errors in the imput data, and there is considerable scope for doing this.

  5. Precise orbit determination of low Earth orbiters using undifferenced GPS data

    NASA Astrophysics Data System (ADS)

    Kuang, Cui-lin; Hou, Fen

    2006-10-01

    Although POD with GPS has been tested using data from various satellites (e.g. CHAMP, GRACE etc.) with different approaches, there are still many open issues concerning the optimum way to determine LEO satellite orbits with GPS. The emphasis of this paper is to develop an efficient method for precise orbit determination of LEOs. To avoid the need for reference measurements from ground-based reference receivers, the analysis is based on an undifferenced processing of GPS code and carrier-phase measurements. The idea was to combine the kinematic and dynamic approaches, by using them interactively, in separate solutions, fitting dynamic orbits to kinematic orbit. So a purely kinematic orbit for the LEOs is obtained simultaneously with the reduced-dynamic orbit. Testing results show the precise of PPP kinematic orbit is about 22cm, and the precise of reduced-dynamic orbit is about 9cm. Also the reduced-dynamic orbit is smoother than PPP kinematic orbit.

  6. The orbital record in stratigraphy

    NASA Technical Reports Server (NTRS)

    Fischer, Alfred G.

    1992-01-01

    Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity, and (2) presence of abundant microfossils yields close ties to geochronology. A tantalizing possibility that stratigraphy may yield a record of orbital signals unrelated to climate has turned up in magnetic studies of our Cretaceous core. Magnetic secular variations here carry a strong 39 ka periodicity, corresponding to the theoretical obliquity period of that time - Does the obliquity cycle perhaps have some direct influence on the magnetic field?

  7. Molecular Orbital Analysis of High Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Ohmura, Shu; Oyamada, Takayuki; Kato, Tsuyoshi; Kono, Hirohiko; Koseki, Shiro

    Tunnel ionization of molecules in an intense laser field and subsequent rescattering processes lead to high harmonic generation (HHG). Simultaneous tunneling from multiple orbitals has recently been observed which is not considered in the conventional single-active-electron model. To include such multielectron effects, we have developed a multiconfiguration method that uses time-dependent molecular orbitals. By energy analysis of the orbitals, we found that inner shell and valence shell orbitals interact with each other during the HHG process. The HHG spectra of multiple orbital paths originated from the interactions were calculated.

  8. TDRSS tracking data and orbit determination evaluation

    NASA Technical Reports Server (NTRS)

    Campion, R. E.; Teles, J.; Pitt, P.

    1984-01-01

    TDRS-1 was launched on April 4, 1983. This paper presents preliminary results of TDRSS tracking data evaluation through September 1983. TDRSS tracking data evaluation is a summary of valid tracking data that characterizes data quality. TDRS-1 orbit accuracy is evaluated by using orbit consistency measured by comparing overlaps of TDRS-1 ephemerides produced from consecutive data arcs. TDRS-1 and user orbit accuracies and consistencies are also estimated. Orbit accuracy is estimated by comparing user orbits based on tracking data obtained both through the TDRSS and from ground-based tracking.

  9. Space Shuttle Orbiter auxiliary power unit status

    NASA Technical Reports Server (NTRS)

    Reck, M.; Loken, G.; Horton, J.; Lukens, W.; Scott, W.; Baughman, J.; Bauch, T.

    1991-01-01

    An overview of the United States Space Shuttle Orbiter APU, which provides power to the Orbiter vehicle hydraulic system, is presented. Three complete APU systems, each with its own separate fuel system, supply power to three dedicated hydraulic systems. These in turn provide power to all Orbiter vehicle critical flight functions including launch, orbit, reentry, and landing. The basic APU logic diagram is presented. The APU includes a hydrazine-powered turbine that drives a hydraulic pump and various accessories through a high-speed gearbox. The APU also features a sophisticated thermal management system designed to ensure safe and reliable operation in the various launch, orbit, reentry, and landing environments.

  10. Management of preseptal and orbital cellulitis

    PubMed Central

    Lee, Seongmu; Yen, Michael T.

    2010-01-01

    Orbital cellulitis describes an infection involving the soft tissues posterior to the orbital septum, including the fat and muscle within the bony orbit. This condition may be associated with severe sight and life-threatening complications. Despite significant advances in antimicrobial therapies and diagnostic technologies, the management of orbital cellulitis often remains challenging, and rapid diagnosis and prompt initiation of therapy are important in minimizing complications and optimizing outcomes. This review summarizes the distinctive characteristics of preseptal and orbital cellulitis, with a focus on anatomic considerations, predisposing conditions, approaches to evaluation, and management strategies. PMID:23960899

  11. On the orbits of computably enumerable sets

    NASA Astrophysics Data System (ADS)

    Cholak, Peter A.; Downey, Rodney; Harrington, Leo A.

    2008-10-01

    The goal of this paper is to show there is a single orbit of the c.e. sets with inclusion, {E} , such that the question of membership in this orbit is ?^1_1 -complete. This result and proof have a number of nice corollaries: the Scott rank of {E} is ?_1^{{CK}}+1 ; not all orbits are elementarily definable; there is no arithmetic description of all orbits of {E} ; for all finite ? ? 9 , there is a properly ?^0_? orbit (from the proof).

  12. Payload/orbiter contamination control requirement study

    NASA Technical Reports Server (NTRS)

    Bareiss, L. E.; Rantanen, R. O.; Ress, E. B.

    1974-01-01

    A study was conducted to determine and quantify the expected particulate and molecular on-orbit contaminant environment for selected space shuttle payloads as a result of major shuttle orbiter contamination sources. Individual payload susceptibilities to contamination are reviewed. The risk of payload degradation is identified and preliminary recommendations are provided concerning the limiting factors which may depend on operational activities associated with the payload/orbiter interface or upon independent payload functional activities. A basic computer model of the space shuttle orbiter which includes a representative payload configuration is developed. The major orbiter contamination sources, locations, and flux characteristics based upon available data have been defined and modeled.

  13. A semi-analytic technique for predicting orbit lifetime of geosynchronous transfer orbits

    NASA Astrophysics Data System (ADS)

    McCormick, B. R.; Fardelos, P. L.; Bond, V. R.

    1986-08-01

    This paper presents a semi-analytic technique for predicting orbit lifetime of geosynchronous transfer orbits. A previous study numerically predicted orbit characteristics that minimize orbit lifetime; however, no geometric explanation for these results was presented. The purpose of this paper is to offer a geometric explanation for these results. This is accomplished by examining the important perturbations affecting orbit lifetime separately and superimposing these results.

  14. Localized and Spectroscopic Orbitals: Squirrel Ears on Water.

    ERIC Educational Resources Information Center

    Martin, R. Bruce

    1988-01-01

    Reexamines the electronic structure of water considering divergent views. Discusses several aspects of molecular orbital theory using spectroscopic molecular orbitals and localized molecular orbitals. Gives examples for determining lowest energy spectroscopic orbitals. (ML)

  15. Pioneer probe mission with orbiter option

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A spacecraft is described which is based on Pioneer 10 and 11, and existing propulsion technology; it can transport and release a probe for entry into Jupiter's atmosphere, and subsequently maneuver to place the spacecraft in orbit about Jupiter. Orbital operations last 3 years and include maneuvers to provide multiple close satellite encounters which allow the orbit to be significantly changed to explore different parts of the magnetosphere. A mission summary, a guide to related documents, and background information about Jupiter are presented along with mission analysis over the complete mission profile. Other topics discussed include the launch, interplanetary flight, probe release and orbit deflection, probe entry, orbit selection, orbit insertion, periapsis raising, spacecraft description, and the effects of Jupiter's radiation belt on both orbiter and the probe.

  16. Orbital inflammatory disease in relapsing polychondritis.

    PubMed

    Teo, Livia; Choo, Chai Teck

    2014-08-01

    We present a 73-year-old Chinese male with bilateral relapsing, remitting orbital inflammatory disease associated with relapsing polychondritis. He first presented with right orbital inflammation that did not improve despite antibiotic treatment. Computer tomography (CT) of the orbits showed a soft tissue mass along the roof of the orbit, which was biopsied, revealing acute on chronic inflammation. There was complete resolution of his orbital inflammation within 2 weeks of initiating systemic steroid treatment. He subsequently developed recurrent bouts of left orbital inflammation. One year later, he was diagnosed with relapsing polychondritis and subsequently developed multiple myeloma seven years later. Comanagement with a rheumatologist will be helpful to achieve control of the disease with judicious use of immunosuppression. Long-term follow-up of the patient will be necessary to monitor for malignant transformation of the orbital lesion, as well as the development of other hematologic malignancies. PMID:24831308

  17. AE 402 Orbital Mechanics The n-Body Problem

    E-print Network

    Gao, Grace Xingxin

    of atmospheric drag effect of Earth oblateness effect of third body (Moon or Sun) on GEO satellite Linear OrbitAE 402 Orbital Mechanics Outline The n-Body Problem equations of motion the two-body problem the elliptic orbit parabolic, hyperbolic, and rectilinear orbits energy of the orbit Position in Orbit

  18. Assembling the Skylab Orbital Workshop

    NASA Technical Reports Server (NTRS)

    1970-01-01

    This photograph was taken during installation of floor grids on the upper and lower floors inside the Skylab Orbital Workshop at the McDornell Douglas plant at Huntington Beach, California. The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment.

  19. Environmental dynamics at orbital altitudes

    NASA Technical Reports Server (NTRS)

    Karr, G. R.

    1976-01-01

    The work reported involved the improvement of aerodynamic theory for free molecular and transition flow regimes. The improved theory was applied to interpretation of the dynamic response of objects traveling through the atmosphere. Satellite drag analysis includes analysis methods, atmospheric super rotation effects, and satellite lift effects on orbital dynamics. Transition flow regimes were studied with falling sphere data and errors resulting in inferred atmospheric parameters from falling sphere techniques. Improved drag coefficients reveal considerable error in previous falling sphere data. The drag coefficient has been studied for the entire spectrum of Knudsen Number and speed ratio, with particular emphasis on the theory of the very low-speed ratio regime.

  20. Lunar resource surveys from orbit

    NASA Technical Reports Server (NTRS)

    Arnold, J. R.

    1977-01-01

    The chemical composition of lunar soil and rocks is known now for nine surface sites, by analysis of returned samples. Three classes of silicate material, mare basalt, KREEP, and highland material (sometimes called ANT) have been identified as major components. Gamma-ray and X-ray instruments have mapped the Apollo 15 and 16 ground tracks for major elements, K, and Th. It is hoped that the Lunar Polar Orbiter will carry instruments capable of producing a chemical map of the entire moon. The most exciting possibility is that ice may exist in shadowed regions near the lunar pole.

  1. Orbital blowout fractures in sport.

    PubMed Central

    Jones, N P

    1994-01-01

    One-third of orbital blowout fractures are sustained during sport. Soccer is most commonly involved. Though visual acuity recovery is usually complete, permanent loss of binocular visual field is almost universal. Typically high-energy blows by opponent's finger, fist, elbow, knee or boot are responsible. Injuries to the eye itself may also be sustained and should be looked for. Ocular protection may be feasible in some sports, but the main preventive measure to be addressed is the reduction in aggressive play or deliberate injury. PMID:7894960

  2. PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS

    SciTech Connect

    Brown, Robert A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: rbrown@stsci.edu

    2009-09-10

    We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevant 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in at least a subset of cases.

  3. The Orbiting Carbon Observatory (OCO)

    NASA Technical Reports Server (NTRS)

    Miller, Charles E.

    2005-01-01

    CO2 is the principal human generated driver of climate change. Accurate forecasting of future climate requires an improved understanding of the global carbon cycle and its interaction with the climate system. The Orbiting Carbon Observatory (OCO) will make global, space-based observations of atmospheric CO2 with the precision, resolution, and coverage needed to understand sources and sinks. OCO data will provide critical information for decision makers including the scientific basis for policy formulation, guide for carbon management strategies and treaty monitoring.

  4. Pearls of Orbital Trauma Management

    PubMed Central

    Roth, Forrest S.; Koshy, John C.; Goldberg, Jonathan S.; Soparkar, Charles N.S.

    2010-01-01

    Orbital fractures account for a significant portion of traumatic facial injuries. Although plastic surgery literature is helpful, additional pearls and insights are provided in this article from the experience of an oculoplastic surgeon. The fundamentals remain the same, but the perceptions differ and provide a healthy perspective on a long-standing issue. The most important thing to remember is that the optimal management plan is often variable, and the proper choice regarding which plan to choose rests upon the clinical scenario and the surgeon having an honest perception of his or her level of expertise and comfort level. PMID:22550464

  5. Viking orbiter stereo imaging catalog

    NASA Technical Reports Server (NTRS)

    Blasius, K. R.; Vetrone, A. V.; Martin, M. D.

    1980-01-01

    The extremely long missions of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of which can be used to form stereo images allowing the earth-bound student of Mars to examine the subject in 3-D. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set. Since that data set is still growing (January, 1980, about 3 1/2 years after the mission began), a second edition of this catalog is planned with completion expected about November, 1980.

  6. Possibilities of lunar polar orbiter

    NASA Astrophysics Data System (ADS)

    Iwata, T.; Nagatomo, M.

    This paper describes the concept of a lunar polar orbiter (LPO), which will map the surface of the moon, especially its polar region and the far side, and send precise images of various wave lengths to earth. The primary purpose of the LPO is to identify global and local structures of lunar resources and topography and to search for a suitable site for the manned lunar base projected for next century. The concept of the LPO is based on the H-II rocket (which has a launch capability to send a rover/lander of one metric ton to the lunar surface) and earth observation technology of Japan.

  7. LLOFX earth orbit to lunar orbit delta V estimation program user and technical documentation

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The LLOFX computer program calculates in-plane trajectories from an Earth-orbiting space station to Lunar orbit in such a way that the journey requires only two delta V burns (one to leave Earth circular orbit and one to circularize into Lunar orbit). The program requires the user to supply the Space Station altitude and Lunar orbit altitude (in km above the surface), and the desired time of flight for the transfer (in hours). It then determines and displays the trans-Lunar injection (TLI) delta V required to achieve the transfer, the Lunar orbit insertion (LOI) delta V required to circularize the orbit around the Moon, the actual time of flight, and whether the transfer orbit is elliptical or hyperbolic. Return information is also displayed. Finally, a plot of the transfer orbit is displayed.

  8. Orbital evolution. [of large natural satellite

    NASA Technical Reports Server (NTRS)

    Burns, J. A.

    1977-01-01

    The orbital evolution of a large satellite is governed primarily by tidal interactions between the satellite and the planet it orbits. Tides raised on a planet by a satellite transfer energy and angular momentum to the satellite orbit; this changes the semimajor axes of satellite orbits, increasing the size of those orbits where the satellite mean motion is smaller than the planetary angular velocity, and decreasing those where the opposite is true. Substantial changes caused by such tides for satellites of the terrestrial planets may explain the absence of satellites about Mercury and Venus. For Jovian and Saturnian satellites, such tides probably are only important in bringing about some of the observed orbital resonances. Tides raised on satellites generally cause decreasing orbital eccentricities, indicating why close satellites always have nearly circular orbits. Different processes of orbital evolution dominate for small bodies; their effects probably are critical in positioning material in the primordial dust cloud so that satellite coagulation may occur. A qualitative description is given of the orbital results of gas drag, radiation pressure, Poynting-Robertson drag and electromagnetic forces.

  9. Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-tail Morphology, and Relationship to New Cluster of Bright Sungrazers

    NASA Astrophysics Data System (ADS)

    Sekanina, Zdenek; Chodas, Paul W.

    2012-10-01

    We describe the physical and orbital properties of C/2011 W3. After surviving perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail were observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Australia. The process of disintegration culminated with a terminal fragmentation event on December 17.6 UT. The postperihelion dust tail, observed for ~3 months, was the product of activity over <2 days. The nucleus' breakup and crumbling were probably caused by thermal stress due to the penetration of the intense heat pulse deep into the nucleus' interior after perihelion. The same mechanism may be responsible for cascading fragmentation of sungrazers at large heliocentric distances. The delayed response to the hostile environment in the solar corona is at odds with the rubble-pile model, since the residual mass of the nucleus, estimated at ~1012 g (equivalent to a sphere 150-200 m across) just before the terminal event, still possessed nontrivial cohesive strength. The high production rates of atomic oxygen, observed shortly after perihelion, are compatible with a subkilometer-sized nucleus. The spine tail—the product of the terminal fragmentation—was a synchronic feature, whose brightest part contained submillimeter-sized dust grains, released at velocities of up to 30 m s-1. The loss of the nuclear condensation prevented an accurate orbital-period determination by traditional techniques. Since the missing nucleus must have been located on the synchrone, whose orientation and sunward tip have been measured, we compute the astrometric positions of this missing nucleus as the coordinates of the points of intersection of the spine tail's axis with the lines of forced orbital-period variation, derived from the orbital solutions based on high-quality preperihelion astrometry from the ground. The resulting orbit gives 698 ± 2 yr for the osculating orbital period, showing that C/2011 W3 is the first member of the expected new, 21st-century cluster of bright Kreutz-system sungrazers, whose existence was predicted by these authors in 2007. From the spine tail's evolution, we determine that its measured tip, populated by dust particles 1-2 mm in diameter, receded antisunward from the computed position of the missing nucleus. The bizarre appearance of the comet's dust tail in images taken only hours after perihelion with the coronagraphs on board the SOHO and STEREO spacecraft is readily understood. The disconnection of the comet's head from the tail released before perihelion and an apparent activity attenuation near perihelion have a common cause—sublimation of all dust at heliocentric distances smaller than about 1.8 solar radii. The tail's brightness is strongly affected by forward scattering of sunlight by dust. From an initially broad range of particle sizes, the grains that were imaged the longest had a radiation-pressure parameter ? ~= 0.6, diagnostic of submicron-sized silicate grains and consistent with the existence of the dust-free zone around the Sun. The role and place of C/2011 W3 in the hierarchy of the Kreutz system and its genealogy via a 14th-century parent suggest that it is indirectly related to the celebrated sungrazer X/1106 C1, which, just as the first-generation parent of C/2011 W3, split from a common predecessor during the previous return to perihelion.

  10. COMET C/2011 W3 (LOVEJOY): ORBIT DETERMINATION, OUTBURSTS, DISINTEGRATION OF NUCLEUS, DUST-TAIL MORPHOLOGY, AND RELATIONSHIP TO NEW CLUSTER OF BRIGHT SUNGRAZERS

    SciTech Connect

    Sekanina, Zdenek; Chodas, Paul W., E-mail: Zdenek.Sekanina@jpl.nasa.gov, E-mail: Paul.W.Chodas@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2012-10-01

    We describe the physical and orbital properties of C/2011 W3. After surviving perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail were observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Australia. The process of disintegration culminated with a terminal fragmentation event on December 17.6 UT. The postperihelion dust tail, observed for {approx}3 months, was the product of activity over <2 days. The nucleus' breakup and crumbling were probably caused by thermal stress due to the penetration of the intense heat pulse deep into the nucleus' interior after perihelion. The same mechanism may be responsible for cascading fragmentation of sungrazers at large heliocentric distances. The delayed response to the hostile environment in the solar corona is at odds with the rubble-pile model, since the residual mass of the nucleus, estimated at {approx}10{sup 12} g (equivalent to a sphere 150-200 m across) just before the terminal event, still possessed nontrivial cohesive strength. The high production rates of atomic oxygen, observed shortly after perihelion, are compatible with a subkilometer-sized nucleus. The spine tail-the product of the terminal fragmentation-was a synchronic feature, whose brightest part contained submillimeter-sized dust grains, released at velocities of up to 30 m s{sup -1}. The loss of the nuclear condensation prevented an accurate orbital-period determination by traditional techniques. Since the missing nucleus must have been located on the synchrone, whose orientation and sunward tip have been measured, we compute the astrometric positions of this missing nucleus as the coordinates of the points of intersection of the spine tail's axis with the lines of forced orbital-period variation, derived from the orbital solutions based on high-quality preperihelion astrometry from the ground. The resulting orbit gives 698 {+-} 2 yr for the osculating orbital period, showing that C/2011 W3 is the first member of the expected new, 21st-century cluster of bright Kreutz-system sungrazers, whose existence was predicted by these authors in 2007. From the spine tail's evolution, we determine that its measured tip, populated by dust particles 1-2 mm in diameter, receded antisunward from the computed position of the missing nucleus. The bizarre appearance of the comet's dust tail in images taken only hours after perihelion with the coronagraphs on board the SOHO and STEREO spacecraft is readily understood. The disconnection of the comet's head from the tail released before perihelion and an apparent activity attenuation near perihelion have a common cause-sublimation of all dust at heliocentric distances smaller than about 1.8 solar radii. The tail's brightness is strongly affected by forward scattering of sunlight by dust. From an initially broad range of particle sizes, the grains that were imaged the longest had a radiation-pressure parameter {beta} {approx_equal} 0.6, diagnostic of submicron-sized silicate grains and consistent with the existence of the dust-free zone around the Sun. The role and place of C/2011 W3 in the hierarchy of the Kreutz system and its genealogy via a 14th-century parent suggest that it is indirectly related to the celebrated sungrazer X/1106 C1, which, just as the first-generation parent of C/2011 W3, split from a common predecessor during the previous return to perihelion.

  11. The three images on the front of this poster show our galactic neighbor, the Andromeda Galaxy. This galaxy, also

    E-print Network

    be spotted with the naked eye as a fuzzy blob. Like our own galaxy, Andromeda is a large spiral galaxy. The top image may look familiar, because it was made with visible light--the light we see with our eyes. It is in a solar, Earth- trailing orbit as it observes the infrared universe. Ultraviolet: Blue in the stars image

  12. Publications of the Astronomical Society of the Pacific, 118: 16901710, 2006 December 2006. The Astronomical Society of the Pacific. All rights reserved. Printed in U.S.A.

    E-print Network

    Moro-Martin, Amaya

    10; published 2006 December 18 ABSTRACT. We provide an overview of the Spitzer Legacy Program for understanding whether our solar system--and its habitable planet--is a common or a rare circumstance. Additional, Tucson, AZ. ogenic space observatory in Earth-trailing orbit. The obser- vatory was launched in 2003

  13. The Spitzer Space Telescope Mission

    Microsoft Academic Search

    M. W. Werner; T. L. Roellig; F. J. Low; G. H. Rieke; M. Rieke; W. F. Hoffmann; E. Young; J. R. Houck; B. Brandl; G. G. Fazio; J. L. Hora; R. D. Gehrz; G. Helou; B. T. Soifer; J. Stauffer; J. Keene; P. Eisenhardt; D. Gallagher; T. N. Gautier; W. Irace; C. R. Lawrence; L. Simmons; J. E. Van Cleve; M. Jura; E. L. Wright; D. P. Cruikshank

    2004-01-01

    The Spitzer Space Telescope, NASA's Great Observatory for infrared astronomy, was launched 2003 August 25 and is returning excellent scientific data from its Earth-trailing solar orbit. Spitzer combines the intrinsic sensitivity achievable with a cryogenic telescope in space with the great imaging and spectroscopic power of modern detector arrays to provide the user community with huge gains in capability for

  14. The spitzer space telescope mission

    Microsoft Academic Search

    M. W. Werner

    2005-01-01

    The Spitzer Space Telescope, NASA’s Great Observatory for infrared astronomy, was launched 2003 August 25 and is returning excellent scientific data from its Earth-trailing solar orbit. Spitzer combines the intrinsic sensitivity achievable with a cryogenic telescope in space with the great imaging and spectroscopic power of modern detector arrays to provide the user community with huge gains in capability for

  15. Safety in earth orbit study. Volume 4: Space shuttle orbiter: Safety requirements and guidelines on-orbit phase

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Safety requirements and guidelines are listed for the space shuttle orbiter and for its interface with other vehicles. The requirements and guidelines are specific to the hazards and emergencies in earth orbit. The requirements and guidelines for the orbiter are those with respect to vehicle design, safety devices, warning devices, operational procedures, and residual hazards. The requirements and guidelines for interface with the space station, upper stage vehicles, and sortie payloads are imposed on these vehicles to ensure the safety of the shuttle orbiter. The rationale for the safety requirements and guidelines is also discussed.

  16. The performance of Space-Based Radars (SBR) orbiting on elliptical orbits

    NASA Astrophysics Data System (ADS)

    Faubert, D.; Kerr, M. P.

    1988-12-01

    The performance of Space-Based Radars (SBR) orbiting on elliptical orbits is discussed. Their ability to detect air-breathing targets is analyzed as a function of the antenna look angle, the orbital parameters of the satellite, the number of radio pulses transmitted and the peak power of the radar. The results show that the minimum detectable velocities of the SBR tend to degrade as the satellite approaches the apogee of its orbit. Depending on the orbital parameters of the satellite, the advantage of more extended coverage when the satellite is at the apogee of its orbit could be hindered by the poorer performance of the radar.

  17. Application of two special orbits in the orbit determination of lunar satellites

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Hou, Xi-Yun; Tang, Jing-Shi; Liu, Lin

    2014-10-01

    Using inter-satellite range data, the combined autonomous orbit determination problem of a lunar satellite and a probe on some special orbits is studied in this paper. The problem is firstly studied in the circular restricted three-body problem, and then generalized to the real force model of the Earth-Moon system. Two kinds of special orbits are discussed: collinear libration point orbits and distant retrograde orbits. Studies show that the orbit determination accuracy in both cases can reach that of the observations. Some important properties of the system are carefully studied. These findings should be useful in the future engineering implementation of this conceptual study.

  18. The Lunar Geosciences Orbiter mission

    NASA Astrophysics Data System (ADS)

    Pine, D.

    1986-06-01

    Current plans for the Lunar Geosciences Orbiter (LGO) are described, noting that its purpose will be to help answer some of the most fundamental questions in lunar science today by mapping the moon's surface to determine the distribution of minerals and elements. The proposed orbiter is part of a series of unmanned flights, only one of which is approved so far: a Mars Observer mission which NASA expects to launch in 1990. The others include a Near Earth Asteroid rendezvous mission, a Mars Aeronomy Observer (studying the upper atmosphere), and LGO. A standardized spacecraft with individually tailored experiments (probably including a mapping spectrometer, a gamma ray spectrometer and a mapping camera) is planned. Unlike Mars, the moon has not been thoroughly mapped; and despite decades of study, its origin has remained a mystery. (A revolutionary new theory, noted in a side-bar, suggests that the moon consists mostly of the mantle of a Mars-sized protoplanet that collided with the earth and merged its iron core with our planet perhaps four billion years ago).

  19. Advances in SLR orbit determination

    NASA Astrophysics Data System (ADS)

    Kolenkiewicz, R.; Smith, D. E.; Dunn, P. J.; Torrence, M. H.

    Since LAGEOS II was launched from the space shuttle in October 1992, the Global Tracking Network has provided an extensive set of Satellite Laser Ranging data which supplement the 20 year record of LAGEOS I. The contrasting behavior of small unmodeled along-track accelerations in the orbits of each satellite can be used to help explain the sources of these perturbations. LAGEOS II's 52 degree inclination provides gravity and tidal sensitivity to improve on the advances from LAGEOS I in a shorter time, as LAGEOS II's nodal precession period is about one half that of LAGEOS I's three year period. The combination of data from the two LAGEOS satellites, together with observations from other geodetic satellites, such as ETALON I and II, allows better definition of polar motion and length-of-day, which can now be resolved at sub-daily intervals during periods of concentrated tracking. The geometry added by LAGEOS II has also been found to improve station positioning accuracy for studies of regional deformation in the vicinity of the laser observatories. The improved SLR global reference frame can now be used to accurately define orbit and station positions from a variety of space and conventional geodetic methods.

  20. Chandrayaan-1, Lunar polar orbiter

    NASA Astrophysics Data System (ADS)

    Bhandari, N.

    Chandrayaan-1 is a lunar polar orbiter mission designed by the Indian Space Research organisation for remote sensing of the lunar surface. The scientific objectives of the proposed mission are simultaneous geochemical, mineralogical and photogeological mapping of the whole lunar surface. The payloads include hyperspectral imager (HySI) for mineralogical mapping, X-ray fluorescence spectrometer (LEX) for elemental mapping, low energy gamma ray spectrometer (HEX) for mapping some radioactive elements, a Terrain mapping camera (TMC) and a Laser altimeter (LLRI), leaving a provision for some additional instruments, which may enhance the capability of this mission in achieving its objectives. A plausible launch scenario using the Polar Satellite Launch Vehicle (PSLV) suggests that a 480 kg lunarcraft, carrying about 60 kg of payloads can be inserted in a 100 km altitude polar orbit around the Moon and can be sustained for two years of observations for total coverage of the lunar surface. The goals and scientific challenges of the mission are discussed in this paper

  1. Achromatic orbital angular momentum generator

    NASA Astrophysics Data System (ADS)

    Bouchard, Frédéric; Mand, Harjaspreet; Mirhosseini, Mohammad; Karimi, Ebrahim; Boyd, Robert W.

    2014-12-01

    We describe a novel approach for generating light beams that carry orbital angular momentum (OAM) by means of total internal reflection in an isotropic medium. A continuous space-varying cylindrically symmetric reflector, in the form of two glued hollow axicons, is used to introduce a nonuniform rotation of polarization into a linearly polarized input beam. This device acts as a full spin-to-orbital angular momentum convertor. It functions by switching the helicity of the incoming beam?s polarization, and by conservation of total angular momentum thereby generates a well-defined value of OAM. Our device is broadband, since the phase shift due to total internal reflection is nearly independent of wavelength. We verify the broad-band behaviour by measuring the conversion efficiency of the device for three different wavelengths corresponding to the RGB colours, red, green and blue. An average conversion efficiency of 95% for these three different wavelengths is observed. This device may find applications in imaging from micro- to astronomical systems where a white vortex beam is needed.

  2. On-orbit Passive Thermography

    NASA Technical Reports Server (NTRS)

    Howell, Patricia A.; Winfree, William P.; Cramer, K. Elliott

    2008-01-01

    On July 12, 2006, British-born astronaut Piers Sellers became the first person to conduct thermal nondestructive evaluation experiments in space, demonstrating the feasibility of a new tool for detecting damage to the reinforced carbon-carbon (RCC) structures of the Shuttle. This new tool was an EVA (Extravehicular Activity, or spacewalk) compatible infrared camera developed by NASA engineers. Data was collected both on the wing leading edge of the Orbiter and on pre-damaged samples mounted in the Shuttle s cargo bay. A total of 10 infrared movies were collected during the EVA totaling over 250 megabytes of data. Images were downloaded from the orbiting Shuttle to Johnson Space Center for analysis and processing. Results are shown to be comparable to ground-based thermal inspections performed in the laboratory with the same type of camera and simulated solar heating. The EVA camera system detected flat-bottom holes as small as 2.54cm in diameter with 50% material loss from the back (hidden) surface in RCC during this first test of the EVA IR Camera. Data for the time history of the specimen temperature and the capability of the inspection system for imaging impact damage are presented.

  3. LROC - Lunar Reconnaissance Orbiter Camera

    NASA Astrophysics Data System (ADS)

    Robinson, M. S.; Eliason, E.; Hiesinger, H.; Jolliff, B. L.; McEwen, A.; Malin, M. C.; Ravine, M. A.; Thomas, P. C.; Turtle, E. P.

    2009-12-01

    The Lunar Reconnaissance Orbiter (LRO) went into lunar orbit on 23 June 2009. The LRO Camera (LROC) acquired its first lunar images on June 30 and commenced full scale testing and commissioning on July 10. The LROC consists of two narrow-angle cameras (NACs) that provide 0.5 m scale panchromatic images over a combined 5 km swath, and a wide-angle camera (WAC) to provide images at a scale of 100 m per pixel in five visible wavelength bands (415, 566, 604, 643, and 689 nm) and 400 m per pixel in two ultraviolet bands (321 nm and 360 nm) from the nominal 50 km orbit. Early operations were designed to test the performance of the cameras under all nominal operating conditions and provided a baseline for future calibrations. Test sequences included off-nadir slews to image stars and the Earth, 90° yaw sequences to collect flat field calibration data, night imaging for background characterization, and systematic mapping to test performance. LRO initially was placed into a terminator orbit resulting in images acquired under low signal conditions. Over the next three months the incidence angle at the spacecraft’s equator crossing gradually decreased towards high noon, providing a range of illumination conditions. Several hundred south polar images were collected in support of impact site selection for the LCROSS mission; details can be seen in many of the shadows. Commissioning phase images not only proved the instruments’ overall performance was nominal, but also that many geologic features of the lunar surface are well preserved at the meter-scale. Of particular note is the variety of impact-induced morphologies preserved in a near pristine state in and around kilometer-scale and larger young Copernican age impact craters that include: abundant evidence of impact melt of a variety of rheological properties, including coherent flows with surface textures and planimetric properties reflecting supersolidus (e.g., liquid melt) emplacement, blocks delicately perched on terraces and rims, and both large and small radial and circumferential ejecta patterns, reflecting their ballistic emplacement and interaction with pre-existing topography and that created by earlier ejecta, extending out more than a crater diameter. Early efforts at reducing NAC stereo observations to topographic models show spatial resolutions of 2.5 m to 5 m will be possible from the 50 km orbit. Systematic seven-color WAC observations will commence at the beginning of the primary mapping phase. A key goal of the LROC experiment is to characterize future exploration targets in cooperation with the NASA Constellation program. By the end of the commissioning phase all fifty high priority targets will have partial reconnaissance mode coverage (0.5 m to 2 m per pixel).

  4. Dynamical friction: effect of chaotic orbits

    NASA Astrophysics Data System (ADS)

    Cora, S. A.; Vergne, M. M.; Muzzio, J. C.

    1998-11-01

    We use numerical experiments to investigate the orbital decay, caused by dynamical friction, of a rigid satellite which moves within a larger stellar system (a galaxy); the self gravity of the particles that make up the galaxy is neglected. We study the influence on dynamical friction of chaotic orbits, present in non-integrable systems. Previous studies suggest that the presence of these orbits could enhance the effect of the dynamical friction; our goal is to verify this hypothesis, since, as much as we know, there are not simulations of this kind made by other authors. The influence of chaos is studied considering pairs of comparable models (similar density distributions) with different percentages of regular and chaotic orbits. For this purpose, we consider a Satoh modified potential to represent the galaxy, that is allowed to move on a circular orbit in a logarithmic potential; the rotation induces the appearence of chaotic orbits.

  5. Orbit keeping attitude control for space station

    NASA Technical Reports Server (NTRS)

    Barrows, D.; Bedell, H.

    1983-01-01

    It is pointed out that on-orbit configuration variability is expected to be a characteristic of a space station. The implementation of such a chracteristic will present reboost and thruster control system designers with a number of new challenges. The primary requirement for the space station orbit reboost (or orbit keeping) system is to ensure system viability for extended duration and prevent an uncontrolled reentry as with Skylab. For a station in a low earth orbit, earodynamic drag will be sufficient to cause relatively quick orbit altitude decay. A propulsion system is, therefore, needed to counteract the aerodynamic drag forces and to boost the vehicle to the desired orbit altitudes. A description is given of a typical reboost operational procedure and propellant requirements. Attention is given to thruster control systems, and aspects of reboost guidance.

  6. he orbit control of ERS-1

    NASA Astrophysics Data System (ADS)

    Rosengren, Mats

    Earth Resources Satellite-1 (ERS-1) launched the 17th of July 1991 into a near-circular, near-polar, sun-synchronous orbit at an approximate altitude of 790 km, is the first remote sensing satellite of the European Space Agency, (ESA). It was first maneuvered into a 3 days/43 orbits repeat cycle and later into a 35 days/501 orbits repeat cycle. The special features of its orbit comparison with other similar projects are: the ground track is maintained in a narrow control dead-band of only +/- 1 km; the orbit is more `frozen' than those of earlier spacecraft as a new theory for the passive eccentricity control is utilized. In this paper the orbit control required for ERS-1 is discussed and it is shown what kind of results that have been obtained. Of special interest is here the low secular drift rate for the eccentricity vector and an analysis of the factors affecting this drift rate.

  7. Orbital Granulomatosis With Polyangiitis (Wegener Granulomatosis)

    PubMed Central

    Muller, Karra; Lin, Jonathan H.

    2014-01-01

    The pathology of granulomatosis with polyangiitis (GPA), formerly Wegener granulomatosis, typically features a granulomatous and sometimes necrotizing vasculitis targeting the respiratory tract and kidneys. However, orbital involvement occurs in up to 60% of patients and is frequently the first or only clinical presentation in patients with systemic or limited forms of GPA. Orbital GPA can cause significant morbidity and potentially lead to complete loss of vision and permanent facial deformity. Fortunately, GPA is highly responsive to medical treatment with corticosteroids combined with cyclophosphamide or, more recently, rituximab. Therefore, it is imperative for this disease to be accurately diagnosed on orbital biopsy and distinguished from other histologically similar orbital lesions. Herein, we review the clinical and pathologic findings of orbital GPA, focusing on the differentiation of this disease from other inflammatory orbital lesions. PMID:25076302

  8. RHIC BPM system average orbit calculations

    SciTech Connect

    Michnoff,R.; Cerniglia, P.; Degen, C.; Hulsart, R.; et al.

    2009-05-04

    RHIC beam position monitor (BPM) system average orbit was originally calculated by averaging positions of 10000 consecutive turns for a single selected bunch. Known perturbations in RHIC particle trajectories, with multiple frequencies around 10 Hz, contribute to observed average orbit fluctuations. In 2006, the number of turns for average orbit calculations was made programmable; this was used to explore averaging over single periods near 10 Hz. Although this has provided an average orbit signal quality improvement, an average over many periods would further improve the accuracy of the measured closed orbit. A new continuous average orbit calculation was developed just prior to the 2009 RHIC run and was made operational in March 2009. This paper discusses the new algorithm and performance with beam.

  9. Orbital debris characterization with impact flash signatures

    SciTech Connect

    Ang, J.A.

    1991-12-31

    Orbital debris is recognized as a serious and growing threat to man`s utilization and exploration of space. While some information is available on the material composition of orbital debris, most measurements of orbital debris size and velocity distributions do not distinguish material type. The analysis and understanding of impact flash signatures can lead to an in-situ detector system with the ability to determine size and impact velocity distribution for orbital debris segregated by material type. This detector concept is based on an understanding of how material shock properties govern the flash signature arising from the impact of a piece of orbital debris (impactor) against a witness plate (target). Analytical results are presented that identify the most promising witness plate materials with respect to producing impact flash signatures that characterize the orbital debris material. 7 refs.

  10. Orbital debris characterization with impact flash signatures

    SciTech Connect

    Ang, J.A.

    1991-01-01

    Orbital debris is recognized as a serious and growing threat to man's utilization and exploration of space. While some information is available on the material composition of orbital debris, most measurements of orbital debris size and velocity distributions do not distinguish material type. The analysis and understanding of impact flash signatures can lead to an in-situ detector system with the ability to determine size and impact velocity distribution for orbital debris segregated by material type. This detector concept is based on an understanding of how material shock properties govern the flash signature arising from the impact of a piece of orbital debris (impactor) against a witness plate (target). Analytical results are presented that identify the most promising witness plate materials with respect to producing impact flash signatures that characterize the orbital debris material. 7 refs.

  11. Orbital Physics in Transition-Metal Oxides

    Microsoft Academic Search

    Y. Tokura; N. Nagaosa

    2000-01-01

    An electron in a solid, that is, bound to or nearly localized on the specific atomic site, has three attributes: charge, spin, and orbital. The orbital represents the shape of the electron cloud in solid. In transition-metal oxides with anisotropic-shaped d-orbital electrons, the Coulomb interaction between the electrons (strong electron correlation effect) is of importance for understanding their metal-insulator transitions

  12. SELENE: The Moon-Orbiting Observatory Mission

    Microsoft Academic Search

    H. Mizutani; M. Kato; S. Sasaki; Y. Iijima; K. Tanaka; Y. Takizawa

    2004-01-01

    The Moon-orbiting SELENE (Selenological and Engineering Explorer) mission is prepared in Japan for lunar science and technology development. The launch target has been changed from 2005 to 2006 because of the launch failure of H2A rocket in 2003. The spacecraft consists of a main orbiting satellite at about 100 km altitude in the polar orbit and two sub-satellites in the

  13. Simulator Study of Lunar Orbit Establishment

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Simulator Study of Lunar Orbit Establishment. The film was made using the Lunar Orbit and Landing Approach Simulator (LOLA). It represents the view an astronaut would see if he were looking toward the lunar horizon just prior to and during retrofire for orbit establishment. During this period the astronaut is essentially flying backward, therefore the lunar surface features appear to be moving away during the flight. [Entire movie available on DVD from CASI as Doc ID 20070030976. Contact help@sti.nasa.gov

  14. How periodic orbit bifurcations drive multiphoton ionization

    E-print Network

    S. Huang; C. Chandre; T. Uzer

    2006-12-26

    The multiphoton ionization of hydrogen by a strong bichromatic microwave field is a complex process prototypical for atomic control research. Periodic orbit analysis captures this complexity: Through the stability of periodic orbits we can match qualitatively the variation of experimental ionization rates with a control parameter, the relative phase between the two modes of the field. Moreover, an empirical formula reproduces quantum simulations to a high degree of accuracy. This quantitative agreement shows how short periodic orbits organize the dynamics in multiphoton ionization.

  15. Some accuracy aspects of satellite orbit prediction

    Microsoft Academic Search

    B. A. C. Ambrosius

    1974-01-01

    A computer program, applicable to the Astronomical Netherlands Satellite (ANS), was developed for long-term prediction of low-earth satellite orbits. The program takes into account perturbations due to the earth's gravitational potential, lunisolar attraction, and aerodynamic drag. The analytical expressions describing long-term orbital-element variations due to zonal harmonic perturbations and a method for predicting the satellite's in-orbit position over one revolution

  16. Long term prediction for high altitude orbits

    Microsoft Academic Search

    S. K. Collins; P. J. Cefola

    1981-01-01

    A first-order theory is developed for the rapid and accurate calculation of secular and long-period changes in the elements of a high-altitude earth orbit due to the action of the sun and moon. The third body disturbing potential is first derived in nonsingular orbital elements with the satellite orbit plane used as the frame of reference and third body resonance

  17. Bilateral orbital emphysema from compressed air injury

    Microsoft Academic Search

    Tina Li; Mahmood F Mafee; Deepak P Edward

    1999-01-01

    PURPOSE: To describe a patient who developed bilateral subconjunctival and orbital emphysema after an automobile tire explosion.METHOD: Case report.RESULTS: A 60-year-old man sustained bilateral ocular injury after a tire explosion. Ophthalmic examination disclosed bilateral subconjunctival air, with no visible conjunctival laceration. Computed tomography showed orbital emphysema, with no evidence of orbital fracture. Follow-up examination 2 weeks after the injury disclosed

  18. Quantum Formulation of Fractional Orbital Angular Momentum

    E-print Network

    J. B. Goette; S. Franke-Arnold; R. Zambrini; Stephen M. Barnett

    2006-11-15

    The quantum theory of rotation angles (S. M. Barnett and D. T. Pegg, Phys. Rev. A, 41, 3427-3425 (1990)) is generalised to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of light modes with fractional orbital angular momentum in the paraxial and non-paraxial regime.

  19. Quantum Formulation of Fractional Orbital Angular Momentum

    E-print Network

    Goette, J B; Franke-Arnold, S; Zambrini, R; Barnett, Stephen M.

    2006-01-01

    The quantum theory of rotation angles (S. M. Barnett and D. T. Pegg, Phys. Rev. A, 41, 3427-3425 (1990)) is generalised to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of light modes with fractional orbital angular momentum in the paraxial and non-paraxial regime.

  20. Large capacity cryopropellant orbital storage facility

    NASA Technical Reports Server (NTRS)

    Schuster, J. R.

    1987-01-01

    A comprehensive study was performed to develop the major features of a large capacity orbital propellant storage facility for the space-based cryogenic orbital transfer vehicle. Projected propellant usage and delivery schedules can be accommodated by two orbital tank sets of 100,000 lb storage capacity, with advanced missions expected to require increased capacity. Information is given on tank pressurization schemes, propellant transfer configurations, pump specifications, the refrigeration system, and flight tests.

  1. Spaceborne radar detection of orbital debris

    Microsoft Academic Search

    J. R. Carl; G. D. Arndt; B. A. Bourgoise; I. Paz

    1993-01-01

    Orbital debris in low-Earth-orbit (LEG) poses an increasing threat to the Space Station Freedom (SSF). A combined ground-based\\/on-orbit radar detection system can provide adequate warning to minimize the collision threat. The paper discusses the unique features on an on-board radar, its contributions to solving the problem, simulation results from modeling of atmospheric effects, and their perturbations upon propagation of debris

  2. Spindle cell lipoma of the orbit.

    PubMed

    Tripathy, Devjyoti; Mittal, Ruchi

    2015-01-01

    A 30-year-old otherwise healthy female patient presented to the oculoplastic service with complaints of gradually increasing proptosis and discomfort of the OD of about 4 months' duration. On imaging, an ill-defined mass was seen in the right orbit which, on biopsy, turned out to be a spindle cell lipoma. Lipomas, the commonest among the mesenchymal soft tissue tumors, are surprisingly of rare occurrence in the orbit, despite the presence of abundant fat in the intraorbital space. The authors describe the presentation, management, and outcome of a rare orbital pathology-an orbital spindle cell lipoma. PMID:24819207

  3. Orbit stability of the ALS storage ring

    SciTech Connect

    Keller, R.; Nishimura, H.; Biocca, A. [and others

    1997-05-01

    The Advanced Light Source (ALS) storage ring, a synchrotron light source of the third generation, is specified to maintain its electron orbit stable within one tenth of the rms beam size. In the absence of a dedicated orbit feed-back system, several orbit-distorting effects were investigated, aided by a new interactive simulation tool, the code TRACY V. The effort has led to a better understanding of the behavior of a variety of accelerator subsystems and in consequence produced a substantial improvement in day-to-day orbit stability.

  4. Determination of GPS orbits to submeter accuracy

    NASA Technical Reports Server (NTRS)

    Bertiger, W. I.; Lichten, S. M.; Katsigris, E. C.

    1988-01-01

    Orbits for satellites of the Global Positioning System (GPS) were determined with submeter accuracy. Tests used to assess orbital accuracy include orbit comparisons from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked 8 hours each day shows rms error below 1 m even when predicted more than 3 days outside of a 1-week data arc. Differential tracking of the GPS satellites in high Earth orbit provides a powerful relative positioning capability, even when a relatively small continental U.S. fiducial tracking network is used with less than one-third of the full GPS constellation. To demonstrate this capability, baselines of up to 2000 km in North America were also determined with the GPS orbits. The 2000 km baselines show rms daily repeatability of 0.3 to 2 parts in 10 to the 8th power and agree with very long base interferometry (VLBI) solutions at the level of 1.5 parts in 10 to the 8th power. This GPS demonstration provides an opportunity to test different techniques for high-accuracy orbit determination for high Earth orbiters. The best GPS orbit strategies included data arcs of at least 1 week, process noise models for tropospheric fluctuations, estimation of GPS solar pressure coefficients, and combine processing of GPS carrier phase and pseudorange data. For data arc of 2 weeks, constrained process noise models for GPS dynamic parameters significantly improved the situation.

  5. GPS as an orbit determination subsystems

    NASA Astrophysics Data System (ADS)

    Fennessey, Richard; Roberts, Pat; Knight, Robin; Vanvolkinburg, Bart

    1995-05-01

    This paper evaluates the use of Global Positioning System (GPS) receivers as a primary source of tracking data for low-Earth orbit satellites. GPS data is an alternative to using range, azimuth, elevation, and range-rate (RAER) data from the Air Force Satellite Control Network antennas, the Space Ground Link System (SGLS). This evaluation is applicable to missions such as Skipper, a joint U.S. and Russian atmosphere research mission, that will rely on a GPS receiver as a primary tracking data source. The Detachment 2, Space and Missile Systems Center's Test Support Complex (TSC) conducted the evaluation based on receiver data from the Space Test Experiment Platform Mission O (STEP-O) and Advanced Photovoltaic and Electronics Experiments (APEX) satellites. The TSC performed orbit reconstruction and prediction on the STEP-0 and APEX vehicles using GPS receiver navigation solution data, SGLS RAER data, and SGLS anglesonly (azimuth and elevation) data. For the STEP-O case, the navigation solution based orbits proved to be more accurate than SGLS RAER based orbits. For the APEX case, navigation solution based orbits proved to be less accurate than SGLS RAER based orbits for orbit prediction, and results for orbit reconstruction were inconclusive due to the lack of a precise truth orbit. After evaluating several different GPS data processing methods, the TSC concluded that using GPS navigation solution data is a viable alternative to using SGLS RAER data.

  6. The NOVA-2 postlaunch orbit adjustment process

    NASA Astrophysics Data System (ADS)

    Heyler, Gene A.

    The NOVA-2 satellite was the last of three `drag free' spacecraft to be placed into the Transit Navigation Systems's constellation of satellites. After its launch from Vandenburg Air Force Base into an initial 510 x 170 nmi near poar orbit, an intensive two-week operations schedule was implemented to : raise the orbit approximately 450 nmi to within .015 sec of desired period, trim eccentricity to within .003, trim inclination to within .006 degrees of requirement, freeze the phase of the spacecraft in orbit relative to the other two `drag free' satellites, dump extra fuel by deliberately fual wasting burns, and transition the spacecraft from a slow spin mode to gravity gradient. This paper will briefly discuss the concept of a `drag free' satellite, the selection of the orbit plane in the constellations, and the derivation of the required final orbit parameters. The paper will also discuss peripheral support needed to assist the OATS (Orbit Adjust and Transfer System) ground software, including attitude determination and maneuvers, orbit determination, and orbit prediction through the burns. However, the specific focus of this paper is on the design and execution of the nine OATS burns that accomplished the orbital maneuvers.

  7. Numerical Mean Element Orbital Analysis with Morbiter

    NASA Technical Reports Server (NTRS)

    Ely, Todd A.

    2010-01-01

    The Morbiter software numerically averages an osculating orbit s equations of motion (EOM) to arrive at the mean orbit s EOMs, which are then numerically propagated to obtain the long-term orbital ephemerides. The long-term evolution characteristics, and stability, of an orbit are best characterized using a mean element propagation of the perturbed, two-body variational equations of motion. The average process eliminates short period terms, leaving only secular and long period effects. Doing this avoids the Fourier series expansions and truncations required by the traditional analytic methods.

  8. Orbital Emphysema Occurring During Weight Lifting.

    PubMed

    Ozdemir, Ozdemir

    2014-01-29

    Abstract Although orbital emphysema is a recognized complication of orbital fractures involving any of the paranasal sinuses, it may develop without any fracture. A 23-year-old man presented with sudden left periorbital swelling during weight lifting in a fitness facility. On the left side, there was periorbital swelling with crepitus in palpation of subcutaneous tissue and conjunctival congestion. Computed tomography showed no fractures in the orbit. The patient was hospitalized. He was treated with empiric antibiotics and non-steroidal antiinflammatory drugs. In three days, the swelling and crepitus had almost disappeared. Seven days later, orbital emphysema had completely resolved. PMID:24475915

  9. Payload/orbiter contamination control assessment support

    NASA Technical Reports Server (NTRS)

    Rantanen, R. O.; Ress, E. B.

    1975-01-01

    The development and use is described of a basic contamination mathematical model of the shuttle orbiter which incorporates specific shuttle orbiter configurations and contamination sources. These configurations and sources were evaluated with respect to known shuttle orbiter operational surface characteristics and specific lines-of-sight which encompass the majority of viewing requirements for shuttle payloads. The results of these evaluations are presented as summary tables for each major source. In addition, contamination minimization studies were conducted and recommendations are made, where applicable, to support the shuttle orbiter design and operational planning for those sources which were identified to present a significant contamination threat.

  10. Landsat-4 orbit determination using TDRSS

    NASA Astrophysics Data System (ADS)

    Oza, D. H.; Niklewski, D. J.; Doll, C. E.; Mistretta, G. D.; Hart, R. C.

    1995-08-01

    This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite (TDRS) System (TDRSS)-user spacecraft, Landsat-4, obtained using a Prototype Filter Smoother (PFS), with the accuracy of an established batch-least-squares system, the Goddard Trajectory Determination System (GTDS). The results of Landsat-4 orbit determination provide useful experience for the Earth Observing System (EOS) series of satellites. The filtered and smoothed PFS orbit solutions were compared with the definitive GTDS orbit solutions for Landsat-4; the root-mean-square (RMS) solution difference was 6.6 meters.

  11. TOPEX/Poseidon orbit acquisition maneuver design

    NASA Technical Reports Server (NTRS)

    Bhat, Ramachandra S.

    1992-01-01

    The current baseline injection orbit for the jointly sponsored NASA/CNES TOPEX/Poseidon mission is near-circular, approximately 30 km below the desired operational orbit altitude and at the operational orbit inclination. A baseline maneuver sequence to retarget from this injection orbit to the desired operational orbit has been designed based upon the expected worst-case 3-sigma injection and maneuver execution errors. The sequence requires seven maneuvers, including an initial calibration burn, and achieves the operational orbit with the desired ground track pattern in 30 days. A delay sensitivity analysis has been conducted to estimate the allowable operational delay for each maneuver without increasing the total orbit acquisition period. The baseline sequence provides back-ups for a one-revolution delay for each maneuver and one-day delay for most maneuvers. It is also shown that a higher injection orbit allows the maneuver sequence to achieve the operational orbit in 26 days under a worst-case scenario.

  12. Measurements of the STS orbiter's angular stability during in-orbit operations

    NASA Technical Reports Server (NTRS)

    Neupert, Werner M.; Epstein, Gabriel L.; Houston, James; Zarechnak, Andrew

    1995-01-01

    We report on measurements of the angular stability, commonly called 'jitter', of the STS Orbiter during normal operations in space. Measurements were carried out by measuring optically the Orbiter's roll and pitch orientation relative to the solar vector as the orbiter was held in a -Z(sub 0) solar inertial orientation (orbiter bay oriented toward the Sun). We also report observations of an interesting perturbation to the orbiter's orientation noted by the crew during the STS-60 mission. These data may be useful in analyzing the in-orbit response of the Orbiter to thruster firings and other applied torques, and may aid in the planning of future experiments that require fine-pointed operations by the orbiter.

  13. Acute traumatic orbital encephalocele related to orbital roof fracture: reconstruction by using porous polyethylene.

    PubMed

    Gazio?lu, Nurperi; Ulu, Mustafa Onur; Ozlen, Fatma; Uzan, Mustafa; Ciplak, Nejat

    2008-07-01

    A case report of acute traumatic orbital encephalocele related to orbital roof fracture and its management were presented. Acute traumatic encephalocele related to orbital roof fracture is unusual. Early diagnosis and treatment are very important since the raised intraorbital pressure may irreversibly damage the optic nerve. Orbital computerized tomography with thin axial and coronal sections should be performed in an acute traumatized patient with a concurrent orbital trauma. Reconstruction of the orbital roof is the key step of the surgical treatment and should be performed in every case. Porous polyethylene (Medpor) has been used for many years in reconstructive surgeries and it is superior to other allografts in many ways. In our case, the orbital roof reconstruction was done by Medpor and the early and late cosmetic results were excellent. The important features of acute traumatic encephalocele secondary to orbital roof fractures in terms of presentation, diagnosis and surgical steps were also stressed. PMID:18781424

  14. Free space laser communication experiments from Earth to the Lunar Reconnaissance Orbiter in lunar orbit

    E-print Network

    Sun, Xiaoli

    Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. ...

  15. Plasmons with orbital angular momentum

    SciTech Connect

    Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Ali, S. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); National Centre for Physics, Shahdra Valley Road, Islamabad 44000 (Pakistan); Thide, B. [Swedish Institute of Space Physics, Angstroem Laboratory, P.O. Box 537, SE-751 21 Uppsala (Sweden)

    2009-11-15

    Electron plasma waves carrying orbital angular momentum are investigated in an unmagnetized collisionless plasma composed of inertial electrons and static ions. For this purpose, the usual plasmon dispersion relation is employed to derive an approximate paraxial equation. The latter is analyzed with a Gaussian beam solution. For a finite angular momentum associated with the plasmon, Laguerre-Gaussian (LG) solutions are employed for solving the electrostatic potential problem which gives approximate solution and is valid for plasmon beams in the paraxial approximation. The LG potential determines the electric field components and energy flux of plasmons with finite angular momentum. Numerical illustrations show that the radial and angular mode numbers strongly modify the profiles of the LG potential.

  16. The Orbital Workshop Shower Compartment

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This photograph shows technicians performing a checkout of the Metabolic Analyzer (center background) and the Ergometer (foreground) in the Orbital Workshop (OWS). The shower compartment is at right. The Ergometer (Skylab Experiment M171) evaluated man's metabolic effectiveness and cost of work in space environment. Located in the experiment and work area of the OWS, the shower compartment was a cylindrical cloth enclosure that was folded flat when not in use. The bottom ring of the shower was fastened to the floor and contained foot restraints. The upper ring contained the shower head and hose. To use the shower, the astronaut filled a pressurized portable bottle with heated water and attached the bottle to the ceiling. A flexible hose cornected the water bottle to a handheld shower head. The astronaut pulled the cylindrical shower wall up into position and bathed, using liquid soap. Both soap and water were carefully rationed, having been premeasured for economical use.

  17. The Orbital Workshop Shower Compartment

    NASA Technical Reports Server (NTRS)

    1972-01-01

    In this photograph, the Orbital Workshop shower compartment was unfolded by technicians for inspection. The shower compartment was a cylindrical cloth enclosure that was folded flat when not in use. The bottom ring of the shower was fastened to the floor and contained foot restraints. The upper ring contained the shower head and hose. To use the shower, the astronaut filled a pressurized portable bottle with heated water and attached the bottle to the ceiling. A flexible hose cornected the water bottle to a handheld shower head. The astronaut pulled the cylindrical shower wall up into position and bathed, using liquid soap. Both soap and water were carefully rationed, having been premeasured for economical use.

  18. Mars Science Laboratory Orbit Determination

    NASA Technical Reports Server (NTRS)

    Kruizinga, Gerhard; Gustafson, Eric; Jefferson, David; Martin-Mur, Tomas; Mottinger, Neil; Pelletier, Fred; Ryne, Mark; Thompson, Paul

    2012-01-01

    Mars Science Laboratory (MSL) Orbit Determination (OD) met all requirements with considerable margin, MSL OD team developed spin signature removal tool and successfully used the tool during cruise, A novel approach was used for the MSL solar radiation pressure model and resulted in a very accurate model during the approach phase, The change in velocity for Attitude Control System (ACS) turns was successfully calibrated and with appropriate scale factor resulted in improved change in velocity prediction for future turns, All Trajectory Correction Maneuvers were successfully reconstructed and execution errors were well below the assumed pre-fight execution errors, The official OD solutions were statistically consistent throughout cruise and for OD solutions with different arc lengths as well, Only EPU-1 was sent to MSL. All other Entry Parameter Updates were waived, EPU-1 solution was only 200 m separated from final trajectory reconstruction in the B-plane

  19. Spin-orbit-coupled superconductivity

    PubMed Central

    Lo, Shun-Tsung; Lin, Shih-Wei; Wang, Yi-Ting; Lin, Sheng-Di; Liang, C.-T.

    2014-01-01

    Superconductivity and spin-orbit (SO) interaction have been two separate emerging fields until very recently that the correlation between them seemed to be observed. However, previous experiments concerning SO coupling are performed far beyond the superconducting state and thus a direct demonstration of how SO coupling affects superconductivity remains elusive. Here we investigate the SO coupling in the critical region of superconducting transition on Al nanofilms, in which the strength of disorder and spin relaxation by SO coupling are changed by varying the film thickness. At temperatures T sufficiently above the superconducting critical temperature Tc, clear signature of SO coupling reveals itself in showing a magneto-resistivity peak. When T < Tc, the resistivity peak can still be observed; however, its line-shape is now affected by the onset of the quasi two-dimensional superconductivity. By studying such magneto-resistivity peaks under different strength of spin relaxation, we highlight the important effects of SO interaction on superconductivity. PMID:24961726

  20. Orbital Dynamics of Low-Earth Orbit Laser-Propelled Space Vehicles

    SciTech Connect

    Yamakawa, Hiroshi [Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 (Japan); Funaki, Ikkoh [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, Kanagawa, 229-8510 (Japan); Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, 277-8561 (Japan)

    2008-04-28

    Trajectories applicable to laser-propelled space vehicles with a laser station in low-Earth orbit are investigated. Laser vehicles are initially located in the vicinity of the Earth-orbiting laser station in low-earth orbit at an altitude of several hundreds kilometers, and are accelerated by laser beaming from the laser station. The laser-propelled vehicles start from low-earth orbit and finally escape from the Earth gravity well, enabling interplanetary trajectories and planetary exploration.

  1. Electronic structure, spin excitations, and orbital ordering in a three-orbital model for iron pnictides

    NASA Astrophysics Data System (ADS)

    Ghosh, Sayandip; Singh, Avinash

    2015-06-01

    A three-orbital itinerant-electron model involving dxz, dyz and dxy Fe 3d orbitals is proposed for iron pnictides towards understanding the (? ,0) ordered magnetism and magnetic excitations in these materials. It is shown that this model at half filling yields a gapped (? ,0) magnetic state, and simultaneously reproduces several experimentally observed features such as the electronic structure, spin excitations, as well as the ferro orbital order between the dxz and dyz orbitals.

  2. LROC - Lunar Reconnaissance Orbiter Camera

    NASA Astrophysics Data System (ADS)

    Robinson, M. S.; Bowman-Cisneros, E.; Brylow, S. M.; Eliason, E.; Hiesinger, H.; Jolliff, B. L.; McEwen, A. S.; Malin, M. C.; Roberts, D.; Thomas, P. C.; Turtle, E.

    2006-12-01

    The Lunar Reconnaissance Orbiter Camera (LROC) is designed to address two of the prime LRO measurement requirements. 1) Assess meter and smaller-scale features to facilitate safety analysis for potential lunar landing sites near polar resources, and elsewhere on the Moon. 2) Acquire multi-temporal synoptic imaging of the poles every orbit to characterize the polar illumination environment (100 m scale), identifying regions of permanent shadow and permanent or near-permanent illumination over a full lunar year. The LROC consists of two narrow-angle camera components (NACs) to provide 0.5-m scale panchromatic images over a 5-km swath, a wide-angle camera component (WAC) to provide images at a scale of 100 and 400 m in seven color bands over a 100-km swath, and a common Sequence and Compressor System (SCS). In addition to acquiring the two LRO prime measurement sets, LROC will return six other high-value datasets that support LRO goals, the Robotic Lunar Exploration Program (RLEP), and basic lunar science. These additional datasets include: 3) meter-scale mapping of regions of permanent or near-permanent illumination of polar massifs; 4) multiple co-registered observations of portions of potential landing sites and elsewhere for derivation of high-resolution topography through stereogrammetric and photometric stereo analyses; 5) a global multispectral map in 7 wavelengths (300-680 nm) to characterize lunar resources, in particular ilmenite; 6) a global 100-m/pixel basemap with incidence angles (60-80°) favorable for morphologic interpretations; 7) sub-meter imaging of a variety of geologic units to characterize physical properties, variability of the regolith, and key science questions; and 8) meter-scale coverage overlapping with Apollo era Panoramic images (1-2 m/pixel) to document the number of small impacts since 1971-1972, to ascertain hazards for future surface operations and interplanetary travel.

  3. Orbit optimization of Mars orbiters for entry navigation: From an observability point of view

    NASA Astrophysics Data System (ADS)

    Yu, Zhengshi; Zhu, Shengying; Cui, Pingyuan

    2015-06-01

    In this paper, the observability of orbiter-based Mars entry navigation is investigated and its application to the orbit optimization of Mars orbiters is demonstrated. An observability analysis of Mars entry navigation processing of range measurements to multiple orbiters based on Fisher information matrix is conducted. The determinant of Fisher information matrix is derived to quantify the degree of observability. The orbit optimization method based on the observability analysis is then proposed. Two navigation scenarios using three and four orbiters are considered in simulations. To verify the advantages of navigation performance, the orbiter-based and ground beacon-based navigation schemes are comparatively analyzed. In the simulation, an Extended Kalman Filter is used to examine the navigation accuracy. It is concluded that the proposed orbit optimization method is able to optimize the orbits of Mars orbiters with the maximum degree of observability. For the Mars entry navigation based on orbiters, a better configuration which is a main contributor to the observability, can be achieved. The navigation performance is more excellent than the ground beacon-based navigation. However, a diminishing return of navigation accuracy is obtained solely by increasing the number of orbiters.

  4. Post-traumatic orbital reconstruction: Anatomical landmarks and the concept of the deep orbit

    Microsoft Academic Search

    B. T. Evans; A. A. C. Webb

    2007-01-01

    Dissection deep within the orbit is a cause for concern to surgeons because of the perceived risks of injuring critical structures such as the contents of the superior orbital fissure and the optic nerve. Although “safe distances” (those distances within which it is considered safe to dissect within the orbit) have been described, these are of limited value if the

  5. Ionospheric refraction effects on orbit determination using the orbit determination error analysis system

    Microsoft Academic Search

    C. P. Yee; D. A. Kelbel; T. Lee; J. B. Dunham; G. D. Mistretta

    1990-01-01

    The influence of ionospheric refraction on orbit determination was studied through the use of the Orbit Determination Error Analysis System (ODEAS). The results of a study of the orbital state estimate errors due to the ionospheric refraction corrections, particularly for measurements involving spacecraft-to-spacecraft tracking links, are presented. In current operational practice at the Goddard Space Flight Center (GSFC) Flight Dynamics

  6. Orbital socket contracture: a complication of inflammatory orbital disease in patients with Wegener’s granulomatosis

    Microsoft Academic Search

    C Talar-Williams; M C Sneller; C A Langford; J A Smith; T A Cox; M R Robinson

    2005-01-01

    Aim: To describe the clinical characteristics of orbital socket contracture in patients with Wegener’s granulomatosis (WG).Methods: A retrospective cohort study The medical records of 256 patients with WG examined at the National Institutes of Health from 1967 to 2004 were reviewed to identify patients with orbital socket contracture. Details of the orbital disease including Hertel exophthalmometry readings, radiological findings, and

  7. Orbit recovery of a low Earth orbiter from GPS and ground tracking stations

    Microsoft Academic Search

    Kaare Aksnes; Dag Hoegvard; Svein Hauge

    1989-01-01

    The use of the PRARE and GPS (Global Positioning System) microwave tracking system is compared for orbit determination of a Low Earth Orbiter (LEO). Because the upward looking GPS system allows much longer contacts times than does the downward looking PRARE system, GPS appears to be superior for this particular application. It is recommended to determine the GPS orbits dynamically

  8. Orbital analysis of a STS (Space Transportation System) external tank in low earth orbit

    Microsoft Academic Search

    Dennis D. Miner

    1987-01-01

    By flying a different launch profile, it is possible for the Space Transportation System's Orbiter to bring the External Tank directly into space. Many studies by NASA and private industry have detailed the potential on-orbit uses of an External Tank. However, at Space Shuttle operating altitudes, an orbiting tank will experience multiple environmental forces resulting in its decay into the

  9. Orbital analysis of a STS (Space Transportation System) external tank in low earth orbit

    NASA Astrophysics Data System (ADS)

    Miner, Dennis D.

    1987-12-01

    By flying a different launch profile, it is possible for the Space Transportation System's Orbiter to bring the External Tank directly into space. Many studies by NASA and private industry have detailed the potential on-orbit uses of an External Tank. However, at Space Shuttle operating altitudes, an orbiting tank will experience multiple environmental forces resulting in its decay into the lower atmosphere and eventual re-entry. This thesis conducts a preliminary study of a single external tank in low earth orbit. Criteria for a parking orbit are defined and, using an orbit prediction computer program with atmospheric drag and gravitational perturbations included, a search is made for the lowest initial altitude that will allow the external tank to remain in this orbit window. The starting altitude that meets the orbit requirements is found to be within reach of the shuttle's capabilities. The orbital elements of this parking orbit are then analyzed and a method for quick calculation of these parameters is devised. An evaluation of the factors that affect the orbital contraction of an external tank is also performed. The atmospheric density and the tank characteristics can both contribute to high orbital decay rates.

  10. Numerical determination of three-dimensional periodic orbits generated from vertical self-resonant satellite orbits

    Microsoft Academic Search

    I. A. Robin; V. V. Markellos

    1980-01-01

    The mechanism by which ‘vertical’ branches consisting of symmetric, three-dimensional periodic orbits bifurcate from families of plane orbits at ‘veertical self-resonant’ orbits is discussed, with emphasis on the relationship between symmetry properties and multiplicity, and methods for the numerical determination of such branches are described. As examples, eight new families of all symmetry classes which branch vertically from the familyf

  11. Atomic Orbitals, Molecular Orbitals and Related Concepts: Conceptual Difficulties among Chemistry Students.

    ERIC Educational Resources Information Center

    Tsaparlis, Georgios

    1997-01-01

    Investigates the impact an undergraduate quantum chemistry course has on students' knowledge and understanding of atomic orbitals, molecular orbitals, and related concepts. Analysis reveals that students do not have a clear understanding of these concepts and confuse the various atomic orbital representations. Includes some suggestions and…

  12. Mars Reconnaissance Orbiter Radio Science Gravity Investigation

    E-print Network

    Zuber, Maria

    data from the Mars Global Surveyor and Mars Odyssey spacecraft, also currently orbiting Mars] and Mars Odyssey (ODY) [Saunders et al., 2004] missions. The combined analysis will maximize the geoMars Reconnaissance Orbiter Radio Science Gravity Investigation Maria T. Zuber,1 Frank G. Lemoine,2

  13. Orbital Analysis for Near-Earth Objects

    NASA Technical Reports Server (NTRS)

    Yeomans, D. K.; Chodas, P. W.

    1995-01-01

    For recently discovered Near-Earth Objects (NEO) two body computations can be used to determine the minimum distance between the object's orbit and that of the Earth. Determinations can then be made for potential near-term threats to the Earth. This preliminary orbit analysis must be followed with planetary perturbation computations of the object's future motion to predict actual close Earth approaches.

  14. Reaction asymmetries and the spin orbit interaction

    NASA Astrophysics Data System (ADS)

    Bond, P. D.

    1984-02-01

    The use of reaction asymmetries to deduce spin orbit interactions in heavy ion reactions is discussed. It is suggested that in most cases they are too sensitive to many other phenomena to be useful tools and reanalysis of some existing data demonstrates that large spin orbit interactions are not required to reproduce the observed asymmetries.

  15. Stationkeeping for the Lunar Reconnaissance Orbiter (LRO)

    NASA Technical Reports Server (NTRS)

    Beckman, Mark; Lamb, Rivers

    2007-01-01

    The Lunar Reconnaissance Orbiter (LRO) is scheduled to launch in 2008 as the first mission under NASA's Vision for Space Exploration. Follo wing several weeks in a quasi-frozen commissioning orbit, LRO will fl y in a 50 km mean altitude lunar polar orbit. During the one year mis sion duration, the orbital dynamics of a low lunar orbit force LRO to perform periodic sets of stationkeeping maneuvers. This paper explor es the characteristics of low lunar orbits and explains how the LRO s tationkeeping plan is designed to accommodate the dynamics in such an orbit. The stationkeeping algorithm used for LRO must meet five miss ion constraints. These five constraints are to maintain ground statio n contact during maneuvers, to control the altitude variation of the orbit, to distribute periselene equally between northern and southern hemispheres, to match eccentricity at the beginning and the end of the sidereal period, and to minimize stationkeeping (Delta)V. This pape r addresses how the maneuver plan for LRO is designed to meet all of the above constraints.

  16. LSST: Comprehensive NEO detection, characterization, and orbits

    Microsoft Academic Search

    Zeljko Ivezic; J. Anthony Tyson; Mario Juric; Jeremy Kubica; Andrew Connolly; Francesco Pierfederici; Alan W. Harris; Edward Bowell

    2007-01-01

    The Large Synoptic Survey Telescope (LSST) is currently by far the most ambitious proposed ground-based optical survey. Design and development and fabrication of long lead components is underway. Solar System mapping is one of the four key drivers, with emphasis on efficient Potentially Hazardous Asteroid (PHA) detection, orbit determination, and characterization. To obtain orbits for a significant fraction of PHAs

  17. Orbital Decay in LMC X-4

    E-print Network

    Alan M. Levine; Saul A. Rappaport; Goce Zojcheski

    2000-05-04

    We report on the results of observations of the binary X-ray pulsar LMC X-4 with the Rossi X-ray Timing Explorer. Our analysis of the Doppler delays of the 13.5-s X-ray pulsations yields the most accurate determination of the LMC X-4 orbital parameters available to date. The epoch of orbital phase zero for the 1.4 day orbit is determined with an uncertainty of about 20 s, and is combined with 5 earlier determinations of the epoch of phase zero to obtain the first high significance measurement of the rate of change in the orbital period. We find that the orbital decay timescale is close to 1,000,000 years. We present data on one of three strong X-ray flares as well as energy-dependent pulse profiles for both non-flaring and flaring time intervals. The pulse profiles during the non-flaring time intervals are typically strikingly different from the flare profiles, but at other times can be similar. We reconsider the orbital decay of LMC X-4 in the context of tidal evolution. We find that, while the orbital decay is most likely driven by tidal interactions, the asynchronism between the orbit and the rotation of the companion star is probably maintained by the evolutionary expansion of the companion star, and that the evidence favors the companion star being in a late stage of its life on the main sequence.

  18. Orbit: an optimizing compiler for scheme

    Microsoft Academic Search

    David Kranz; Richard Kelsey; Jonathan Rees; Paul Hudak; James Philbin; Norman Adams

    2004-01-01

    Orbit was an optimizing compiler for T, a dialect of Scheme. Its aggressive use of CPS conversion, novel closure representations, and efficient code generation strategies made it the best compiler for a Scheme dialect at the time and for many years to come. The design of T and Orbit directly spawned six PhD theses and one Masters thesis, and influenced

  19. STUDY OF ORBIT FEEDBACK SYSTEMS FOR THE

    Microsoft Academic Search

    R. Lorenz; I. Reyzl; S. Sabah

    1998-01-01

    In order to reduce the influence of magnet vibrations which can cause luminosity reduction in the TESLA Linear Col- lider, several feedback loops are planned to control the beam orbit and to keep the beams in collision. The com- plete control system for orbit correction can be divided into three different feedback systems: in the main linac a slow feedback

  20. Rendezvous radar for Space Shuttle Orbiter vehicle

    Microsoft Academic Search

    W. F. McQuillan; A. W. Bologna; D. M. Calabrese

    1974-01-01

    To successfully complete many of the Space Shuttle Program proposed missions involving Orbiter rendezvous with orbiting satellites, some method of detecting and tracking remote targets is desirable. Several studies to establish the requirements for a rendezvous radar system indicated the feasibility of the concept. Extensive application of state of the art components is possible, and system parameters can be determined

  1. Space Shuttle Orbiter onboard rendezvous navigation

    Microsoft Academic Search

    M. J. Little

    1982-01-01

    Much of the work that the Space Shuttle will perform requires a capability to rendezvous with other orbiting objects. The formulation and design philosophy behind the Space Shuttle Orbiter rendezvous navigation system are the subjects of this paper. The current rendezvous navigation design incorporates a Kalman filter to estimate the relative position and velocity. The filter is augmented with state

  2. Relative orientation of orbits in triple stars

    Microsoft Academic Search

    M. F. Sterzik; A. A. Tokovinin

    2002-01-01

    Statistical analysis of the relative alignment of inner and outer orbits in triple systems resulting from a dynamical decay of small-N clusters (N le10 ) is presented and compared to the statistics of real multiple stars. The distribution of the relative angle Phi between the angular momentum vectors of inner and outer orbits in triple stars formed by decay is

  3. Sealing member for orbital or rotary motors

    Microsoft Academic Search

    Sarich

    1980-01-01

    An orbital engine has a piston member journalled on a shaft within a housing to orbit therein upon rotation of the shaft. A plurality of vanes form with the housing and piston member a plurality of variable volume chambers. An annular sealing member is mounted in a recess in a radial face of the piston member and engages an opposed

  4. The ELETTRA Fast Digital Local Orbit Feedback

    Microsoft Academic Search

    C. J. Bocchetta; D. Bulfone; A. Galimberti; D. Giuressi; M. Lonza; C. Scafuri; L. Tosi; R. Visintini

    An overview is given of the ELETTRA Fast Digital Local Orbit Feedback system. The system has been developed to stabilize the electron orbit in the Insertion Device straight sections. It uses two Photon Beam Position Monitors as detectors and four corrector magnets to act on the electron beam. The controller relies on a Digital Signal Processor (DSP) system based on

  5. The Low Earth Orbit Business Center

    Microsoft Academic Search

    D. G. Bienhoff; T. W. Fox

    1981-01-01

    The Low Earth Orbit Business Center (LEOBC) is a manufacturing\\/research facility, similar to a suburban commercial center, conceived to exploit the unique environment of Low Earth Orbit (LEO). The LEOBC is a two-floor torus connected to a large hub by four spokes. Up to 82 lease units and comfortable residential support for up to 400 personnel are provided in the

  6. Spacecraft orbit determination using GPS navigation solutions

    Microsoft Academic Search

    Jae-Cheol Yoon; Byoung-Sun Lee; Kyu-Hong Choi

    2000-01-01

    The orbit determination using the GPS navigation solutions for the KOMPSAT-1 spacecraft has been studied. The Cowell method of special perturbation theories was employed to develop a precision orbit propagation, and the perturbations due to geopotential, the gravity of the Sun and the Moon, solid Earth tides, ocean tides, the Earth's dynamic polar motion, solar radiation pressure, and atmospheric drag

  7. Giant Solitary Fibrous Tumor of Orbit.

    PubMed

    Tenekeci, Goktekin; Sari, Alper; Vayisoglu, Yusuf; Serin, Onur

    2015-07-01

    Solitary fibrous tumors (SFTs) have been reported in various locations in the body. Solitary fibrous tumors are extremely rare tumors, especially when located in the orbit. Diagnosis of SFT cannot be made based on histopathology only because it exhibits a variable microscopic appearance, and necessitates immunohistochemistry to confirm the diagnosis.A 51-year-old man was admitted to our clinic for the evaluation of a mass bulging in his left eye. Clinical examination revealed a painless mass extruding out of the orbital cavity with dimensions of 8?×?7?cm. Exenteration of the left eye including the upper and lower eyelid and reconstruction of the orbital cavity using a temporoparietal fascia flap and a temporal muscle flap was performed.SFT of orbital region is known as a slow growing and painless tumor. Based on previous studies, increased mitotic rate of the tumor gives the impression that the tumor has a malignant nature. Until now a small number or orbital SFTs were reported and none of them presented with a giant mass protruding out of the orbital cavity. We present a unique case of orbital SFT filling the whole orbital cavity and protruding outward as a giant mass. This case has been reported to expand our knowledge in this debated entity. PMID:26102546

  8. Long-term orbital lifetime predictions

    Microsoft Academic Search

    P. E. Dreher; A. T. Lyons

    1990-01-01

    Long-term orbital lifetime predictions are analyzed. Predictions were made for three satellites: the Solar Max Mission (SMM), the Long Duration Exposure Facility (LDEF), and the Pegasus Boiler Plate (BP). A technique is discussed for determining an appropriate ballistic coefficient to use in the lifetime prediction. The orbital decay rate should be monitored regularly. Ballistic coefficient updates should be done whenever

  9. Orbiting mechanism in alpha-40Ca scattering

    Microsoft Academic Search

    I. Parija; R. K. Satpathy; C. S. Shastry

    1984-01-01

    The large angle oscillations in several cases of alpha-40Ca scattering are examined in terms of orbital amplitude and the background amplitude interference using the approach developed recently to analyze 16O-28Si scattering. [NUCLEAR REACTIONS alpha-40Ca scattering, anomalous large angle scattering, orbiting phenomena.

  10. Near Earth Objects Program: Orbit Diagrams

    NSDL National Science Digital Library

    NASA JPL Near Earth Object Program

    This page provides access to diagrams of the orbits of a very large number of objects in the asteroid belt as well as comets that cross Earth's orbit. The collection is searchable by object name or designation and users can also browse through an extensive list of potentially hazardous asteroids.

  11. On-Orbit Propulsion OMS/RCS

    NASA Technical Reports Server (NTRS)

    Hurlbert, Eric A.

    2001-01-01

    This slide presentation reviews the Space Shuttle's On-Orbit Propulsion systems: the Orbital Maneuvering System (OMS) and the Reaction Control System (RCS). The functions of each of the systems is described, and the diagrams of the systems are presented. The OMS/RCS thruster is detailed and a trade study comparison of non-toxic propellants is presented.

  12. Quantum formulation of fractional orbital angular momentum

    Microsoft Academic Search

    J. B. Götte; S. Franke-Arnold; R. Zambrini; Stephen M. Barnett

    2007-01-01

    The quantum theory of rotation angles (S. M. Barnett and D. T. Pegg, Phys. Rev. A, 41, 3427-3425 (1990)) is generalised to non-integer values of the orbital angular momentum. This requires the introduction of an additional parameter, the orientation of a phase discontinuity associated with fractional values of the orbital angular momentum. We apply our formalism to the propagation of

  13. Magnetic and orbital excitations in manganese oxides

    Microsoft Academic Search

    W. Koshibae; S. Ishihara; Y. Kawamura; S. Okamoto; J. Inoue; S. Maekawa

    1997-01-01

    The magnetic and orbital structures in manganese oxides with perovskite structure are examined by using the exact diagonalization method on finite-size clusters. The orbital degeneracy in the eg states is taken into account based on the effective Hamiltonian derived in the insulating state with strong Coulomb interaction. It is shown that A-, C- and G-type antiferromagnetic ordering occur as a

  14. The evolution of eccentric protoplanetary orbits

    Microsoft Academic Search

    M. M. Woolfson

    2003-01-01

    The migration of planets has usually been considered in relation to circular orbits of protoplanets for which type I and II migration mechanisms are appropriate. There are theories for planetary origin in which protoplanets are produced in extended eccentric orbits requiring a different theoretical treatment. The basic mechanism for the action of a resisting medium involves gravitational interaction with the

  15. Orbit lifetime prediction and safety considerations

    Microsoft Academic Search

    J. de Lafontaine; R. Mamen

    1984-01-01

    Many space missions involving the employment of man-made satellites require orbits relatively close to the earth's surface. The satellites in low earth orbit (LEO) slowly lose energy, and eventually decay in the lower atmosphere. Normally, a complete breakup of the spacecraft, accompanied by ablation and vaporization, precludes ground impact. Up until now, direct satellite impacts have not been found responsible

  16. Students' Understanding of Orbitals: A Survey.

    ERIC Educational Resources Information Center

    MacKinnon, Gregory R.

    The study of chemistry includes many abstract concepts that students may find difficult to understand. A fundamental yet troublesome part of introductory chemistry courses is the topic of electron configuration and specifically quantum-mechanical orbitals. In an effort to examine the way students internalize the concept of atomic orbitals and how…

  17. Natural bond orbital analysis of steric interactions

    Microsoft Academic Search

    J. K. Badenhoop; F. Weinhold

    1997-01-01

    We describe an ab initio procedure for extracting the Pauli exchange antisymmetry (“steric”) contributions to molecular potential energy in the framework of self-consistent-field molecular orbital (SCFMO) theory. This “natural steric analysis” method is based on natural bond orbital (NBO) representation of the SCFMO wave function, which allows the steric exchange energy to be approximated as an energy difference between “preorthogonal”

  18. Spin-orbital texture in topological insulators.

    PubMed

    Zhang, Haijun; Liu, Chao-Xing; Zhang, Shou-Cheng

    2013-08-01

    For three-dimensional topological insulators in the Bi2Se3 family, topological surface states with p(z) orbitals have a left-handed spin texture for the upper Dirac cone and a right-handed spin texture for the lower Dirac cone. In this work, we predict a new form of the spin-orbital texture associated with the p(x) and p(y) orbitals. For the upper Dirac cone, a left-handed (right-handed) spin texture is coupled to the "radial" ("tangential") orbital texture, whereas for the lower Dirac cone, the coupling of spin and orbital textures is the exact opposite. The "tangential" ("radial") orbital texture is dominant for the upper (lower) Dirac cone, leading to the right-handed spin texture for the in-plane orbitals of both the upper and lower Dirac cones. A spin-resolved and photon polarized angle-resolved photoemission spectroscopy experiment is proposed to observe this novel spin-orbital texture. PMID:23971598

  19. Congenital malignant rhabdoid tumor of the orbit

    Microsoft Academic Search

    D. Brian Stidham; Richard A. Burgett; Mary M. Davis; David A. Plager

    1999-01-01

    Malignant rhabdoid tumor is a rare and highly malignant renal tumor of infancy. Extrarenal tumors involving the orbit have been reported, but never at birth.1-5 The authors describe a primary malignant rhabdoid tumor of the orbit in a neonate who had massive unilateral proptosis at birth. Clinical, radiographic, and histologic features of the tumor are discussed.

  20. Inverse-Square Orbits: A Geometric Approach.

    ERIC Educational Resources Information Center

    Rainwater, James C.; Weinstock, Robert

    1979-01-01

    Presents a derivation of Kepler's first law of planetary motion from Newtonian principles. Analogus derivations of the hyperbolic and parabolic orbits of nonreturning comets and the hyperbolic orbit for a particle in a repulsive inverse-square field are also presented. (HM)

  1. Orbital debris as detected on exposed spacecraft

    Microsoft Academic Search

    R. P. Bernhard; E. L. Christiansen; D. E. Kessler

    1997-01-01

    Spacecraft surfaces returned to the laboratory after being exposed to the low Earth orbit (LEO) environment have been examined by Scanning Electron Microscopy and Energy Dispersive X-ray (SEM\\/EDX) over the last two decades. Although many of these surfaces were not intended to be used as hypervelocity impact capture medium, meteoroid and orbital debris particles colliding with exposed surfaces are well

  2. Haystack measurements of the orbital debris environment

    Microsoft Academic Search

    T. J. Settecerri; E. G. Stansbery; M. J. Matney

    1999-01-01

    The Haystack radar has been observing the orbital debris environment since October 1990. These measurements have provided orbital debris researchers with two important tools for characterizing the environment: 1) the ability to detect small size debris objects from previously unknown sources and 2) the ability to extend the size distribution from the catalog limit (?10 cm) down to 0.5 cm.

  3. MORO: An European Moon Orbiting Observatory

    Microsoft Academic Search

    B. H. Foing; G. Racca

    1996-01-01

    We present the MORO Moon Orbiting Observatory during its phase A study. The context for ESA Intermediate mission M3 is described. We discuss general objectives for scientific lunar studies, specific reasons for a new orbiter around the Moon, and describe the science objectives of MORO and the MORO instruments and mission.

  4. Endgame strategies for planetary moon orbiters

    Microsoft Academic Search

    Ryan Woolley

    2010-01-01

    Delivering an orbiter to a planetary moon such as Titan or Europa requires an exorbitant amount of fuel if the trajectory is not carefully and cleverly planned. V-infinity leveraging maneuvers are an effective means to reduce total Delta-V requirements to achieve orbit about a planetary satellite. This work seeks to characterize optimal trajectories making use of flybys, leveraging maneuvers, and

  5. Polynomial equations for science orbits around Europa

    NASA Astrophysics Data System (ADS)

    Cinelli, Marco; Circi, Christian; Ortore, Emiliano

    2015-07-01

    In this paper, the design of science orbits for the observation of a celestial body has been carried out using polynomial equations. The effects related to the main zonal harmonics of the celestial body and the perturbation deriving from the presence of a third celestial body have been taken into account. The third body describes a circular and equatorial orbit with respect to the primary body and, for its disturbing potential, an expansion in Legendre polynomials up to the second order has been considered. These polynomial equations allow the determination of science orbits around Jupiter's satellite Europa, where the third body gravitational attraction represents one of the main forces influencing the motion of an orbiting probe. Thus, the retrieved relationships have been applied to this moon and periodic sun-synchronous and multi-sun-synchronous orbits have been determined. Finally, numerical simulations have been carried out to validate the analytical results.

  6. Autonomous orbital navigation using Kepler's equation

    NASA Technical Reports Server (NTRS)

    Boltz, F. W.

    1974-01-01

    A simple method of determining the six elements of elliptic satellite orbits has been developed for use aboard manned and unmanned spacecraft orbiting the earth, moon, or any planet. The system requires the use of a horizon sensor or other device for determining the local vertical, a precision clock or timing device, and Apollo-type navigation equipment including an inertial measurement unit (IMU), a digital computer, and a coupling data unit. The three elements defining the in-plane motion are obtained from simultaneous measurements of central angle traversed around the planet and elapsed flight time using a linearization of Kepler's equation about a reference orbit. It is shown how Kalman filter theory may also be used to determine the in-plane orbital elements. The three elements defining the orbit orientation are obtained from position angles in celestial coordinates derived from the IMU with the spacecraft vertically oriented after alignment of the IMU to a known inertial coordinate frame.

  7. Shuttle Orbiter stellar-inertial reference system

    NASA Astrophysics Data System (ADS)

    Smith, F. E.; Campbell, M. E.; Blucker, T. J.; Manry, C. E.; Saulietis, I.

    1983-12-01

    The results of a comparative orbit determination study of four global atmospheric density models (modified Harris-Priester, Jacchia-Roberts, Mass Spectrometer/Incoherent Scatter (MSIS), and Simple Exponential Model (SEM)) are presented. Utilizing these models, definitive orbit determination consistency and accuracy are evaluated using the maximum position differences that occur during 6-hour overlap periods between ephemerides generated from 30-hour data arcs. Propagated ephemerides are compared with definitive orbit solutions to evaluate predictive accuracy. The results indicate that, for satellites above 300 kilometers, all four atmospheric density models produce comparable orbit determination accuracies when an atmospheric drag scaling factor and the satellite state vector are estimated in the orbit determination process.

  8. Satellite Constellation Orbit Evaluation (SCORE) program

    NASA Astrophysics Data System (ADS)

    Russell, L. C.

    1990-04-01

    The objective of this research was to produce a flexible, user-friendly, PC-based computer program that could assist in evaluating satellite constellations. The program would need the capability to graphically display various facets of satellite orbits and communication coverages. Both low earth-orbit and high earth-orbit satellites, would need to be evaluated. The Satellite Constellation Orbit Evaluation Program (SCORE) can be used to graphically display satellite orbits and communication coverages. Although originally developed for the Navy/Defense Advanced Research Projects Agency Satellite Laser Communications (SLC) Program, SCORE can be used to assist in the evaluation of any satellite-communication or surveillance system. A DOS floppy disk containing the executable code for SCORE is included with this report.

  9. Solitary infantile myofibroma of the orbital bone.

    PubMed

    Nam, Dong Heun; Moon, Hyun Seung; Chung, Dong Hae; Baek, Se Hyun

    2005-10-01

    Infantile myofibroma of the orbit is an extremely rare condition. Only a few instances of this condition have ever been reported. A 3-year-old boy visited our clinic with lateral lower eyelid swelling and a palpable mass in the left eye, which had apparently persisted for 2 months. A computed tomography scan revealed a well-circumscribed mass in the inferolateral orbital portion of the zygomatic bone, coupled with erosion of bone and orbital extension with reactive hyperostosis. Immunohistochemical stains proved positive for smooth muscle actin, supporting the diagnosis of solitary infantile myofibroma of the orbital bone (zygoma). Although rarely found in the orbit, solitary infantile myofibroma can display more aggressive or malignant neoplasm. Immunohistochemistry is integral to the differential diagnosis and a systemic evaluation for multicentric myofibroma is essential. PMID:16181295

  10. Numerical experiments on planetary orbits in double stars

    Microsoft Academic Search

    R. Dvorak

    1984-01-01

    This is a numerical study of orbits in the elliptic restricted three-body problem concerning the dependence of the critical orbits on the eccentricity of the primaries. They are defined as being the separatrix between stable and unstable single periodic orbits. As our results are adapted to the existence of planetary orbits in double stars we concentrated first on the P-orbits

  11. Collision activities in the future orbital debris environment

    Microsoft Academic Search

    J.-C. Liou

    2006-01-01

    We have analyzed potential collision activities among orbiting objects for the next 100 years from the low Earth orbit (LEO), medium Earth orbit (MEO), to geosynchronous orbit (GEO) regions. The analysis was based on results from the NASA orbital debris evolutionary model, LEGEND. A total of 30 Monte-Carlo simulations were performed. The 1996-to-2003 launch cycle was repeated in the future

  12. Hypersonic aerodynamic characteristics of NR-ATP orbiter, orbiter with external tank, and ascent configuration

    NASA Technical Reports Server (NTRS)

    Ashby, G. C., Jr.

    1973-01-01

    A scale model of the North American Rockwell ATP Orbiter with and without the external tank has been tested in a 22-inch helium tunnel at Mach 20 and a Reynolds number based on model length, of 2.14 times one million. Longitudinal and lateral-directional data were determined for the orbiter alone while only longitudinal characteristics and elevon roll effectiveness were investigated for the orbiter/tank combination. Oil flow and electron beam flow visualization studies were conducted for the orbiter alone, orbiter with external tank and the ascent configuration.

  13. The Solar Poynting-Robertson Effect On Particles Orbiting Solar System Bodies: Circular Orbits

    NASA Technical Reports Server (NTRS)

    Rubincam, David P.

    2013-01-01

    The Poynting-Robertson effect from sunlight impinging directly on a particle which orbits a Solar System body (planet, asteroid, comet) is considered from the Sun's rest frame. There appear to be no significant first-order terms in V(sub b)/c for circular orbits, where V(sub b) is the body's speed in its orbit about the Sun and c is the speed of light, when the particle's orbital semimajor axis is much smaller than the body's orbital semimajor axis about the Sun as is mainly the case in the Solar System.

  14. Analysis of parking orbits for a STS external tank in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Cross, James E.

    1990-11-01

    A study was conducted of a single external tank in low earth orbit. Criteria for a parking orbit are then defined. Various orbits are then selected by varying the semi-major axis, eccentricity, and inclination. The resulting equations of motion for each of the above orbits (including atmospheric drag and a 2x0 gravity model) are numerically integrated over a time span of 90 earth days. An examination was made of the lowest initial altitudes which allowed the external tank to remain in the orbit window.

  15. Organics, Earth orbit and astrobiology

    NASA Astrophysics Data System (ADS)

    Brack, A.

    Space technology provides the vehicle for transporting terrestrial organic matter and minerals in Earth orbit in order to study in situ their responses to space conditions and to atmospheric entry. Amino acids and peptides were exposed in Earth orbit during two Biopan ESA flights (1994, 1997) and during the CNES Perseus-Exobiologie mission (1999) with exposure times of 14, 10 and 97 days, respectively. The samples were studied with respect of chemical degradation, racemization and possible oligomerization. The samples were exposed as solid films as well as embedded in mineral material (montmorillonite clay, basalt powder and Allende meteorite powder). After three month exposure, about 50% of the amino acids were destroyed in the absence of mineral shielding. Among the different minerals used, meteoritic powder offered the best protection whereas montmorillonite was the less efficient. Different thicknesses of meteorite powder films were used to estimate the shielding threshold. Significant protection from solar radiation was observed when the thickness of the meteorite mineral was 5 ?m or greater. No polymerization occured and no conversion of L-amino acids into the D amino acids was observed. The "STONE" experiment, flown by ESA, was designed to test whether Martian sedimentary material could survive terrestrial atmospheric entry. A basalt (inflight control), a dolomite (sedimentary rock) and artificial Martian regolith were embedded into the ablative heat shield of Foton 12, which was launched on September 1999. The collected entry samples have been analysed for their chemistry, mineralogy and isotopic compositions. Modifications due to atmospheric infall were tested by reference to the untreated samples. The dolomite sample was retrieved intact, although reduced to a depth of about 30% of its original thickness, suggesting that some Martian sediments could, in part, survive terrestrial atmospheric entry from space. Some kinetic isotopic fractionation accompanied the thermal degradation of the dolomite during re-entry, as evidenced by bulk isotopic measurements on different zones of the residual carbonate. The silica "fusion crust" from the associated sample holder exhibited a significant degree of isotopic exchange with atmospheric oxygen during re-entry.

  16. Projected seniority-two orbital optimization of the antisymmetric product of one-reference orbital geminal

    NASA Astrophysics Data System (ADS)

    Boguslawski, Katharina; Tecmer, Pawe?; Limacher, Peter A.; Johnson, Paul A.; Ayers, Paul W.; Bultinck, Patrick; De Baerdemacker, Stijn; Van Neck, Dimitri

    2014-06-01

    We present a new, non-variational orbital-optimization scheme for the antisymmetric product of one-reference orbital geminal wave function. Our approach is motivated by the observation that an orbital-optimized seniority-zero configuration interaction (CI) expansion yields similar results to an orbital-optimized seniority-zero-plus-two CI expansion [L. Bytautas, T. M. Henderson, C. A. Jimenez-Hoyos, J. K. Ellis, and G. E. Scuseria, J. Chem. Phys. 135, 044119 (2011)]. A numerical analysis is performed for the C2 and LiF molecules, for the CH2 singlet diradical as well as for the symmetric stretching of hypothetical (linear) hydrogen chains. For these test cases, the proposed orbital-optimization protocol yields similar results to its variational orbital optimization counterpart, but prevents symmetry-breaking of molecular orbitals in most cases.

  17. Geostationary Orbit Surveillance Using the Unscented Kalman Filter and the Analytical Orbit Model

    NASA Astrophysics Data System (ADS)

    Roh, Kyoung-Min; Park, Eun-Seo; Choi, Byung-Kyu

    2011-09-01

    A strategy for geostationary orbit (or geostationary earth orbit [GEO]) surveillance based on optical angular observations is presented in this study. For the dynamic model, precise analytical orbit model developed by Lee et al. (1997) is used to improve computation performance and the unscented Kalman filer (UKF) is applied as a real-time filtering method. The UKF is known to perform well under highly nonlinear conditions such as surveillance in this study. The strategy that combines the analytical orbit propagation model and the UKF is tested for various conditions like different level of initial error and different level of measurement noise. The dependencies on observation interval and number of ground station are also tested. The test results shows that the GEO orbit determination based on the UKF and the analytical orbit model can be applied to GEO orbit tracking and surveillance effectively.

  18. Study on reduced-dynamic orbit determination of low Earth orbiters

    NASA Astrophysics Data System (ADS)

    Han, Bao-min

    2007-11-01

    Some orbit determination methods using onboard GPS Observations were discussed firstly in this paper, especially the principle and mathematical model of reduced-dynamic Precise Orbit Determination (POD) of Low Earth Satellite (LEO) based on undifferenced spaceborne dual-frequency GPS data. Then a weeklong (from July 28, 2003 to August 3,2003) dual-frequency onboard GPS observation from CHAMP satellite was computed using reduced-dynamic POD. Compared with TUM solutions, our CHAMP orbiting results of one week using reduced dynamic POD method are within 8 centimeters, which can meet the requirements of some higher precision orbit satellite orbits. In order to obtain high precision orbiting results, the impact of different gravity models and proper interval of pseudo-stochastic-pulses on the orbit determination accuracy were analyzed as well.

  19. Diagrammatic theory of transition of pendulum like systems. [orbit-orbit and spin-orbit gravitational resonance interactions

    NASA Technical Reports Server (NTRS)

    Yoder, C. F.

    1979-01-01

    Orbit-orbit and spin-orbit gravitational resonances are analyzed using the model of a rigid pendulum subject to both a time-dependent periodic torque and a constant applied torque. First, a descriptive model of passage through resonance is developed from an examination of the polynomial equation that determines the extremes of the momentum variable. From this study, a probability estimate for capture into libration is derived. Second, a lowest order solution is constructed and compared with the solution obtained from numerical integration. The steps necessary to systematically improve this solution are also discussed. Finally, the effect of a dissipative term in the pendulum equation is analyzed.

  20. Extended Duration Orbiter Medical Project

    NASA Technical Reports Server (NTRS)

    Sawin, Charles F. (Editor); Taylor, Gerald R. (Editor); Smith, Wanda L. (Editor); Brown, J. Travis (Technical Monitor)

    1999-01-01

    Biomedical issues have presented a challenge to flight physicians, scientists, and engineers ever since the advent of high-speed, high-altitude airplane flight in the 1940s. In 1958, preparations began for the first manned space flights of Project Mercury. The medical data and flight experience gained through Mercury's six flights and the Gemini, Apollo, and Skylab projects, as well as subsequent space flights, comprised the knowledge base that was used to develop and implement the Extended Duration Orbiter Medical Project (EDOMP). The EDOMP yielded substantial amounts of data in six areas of space biomedical research. In addition, a significant amount of hardware was developed and tested under the EDOMP. This hardware was designed to improve data gathering capabilities and maintain crew physical fitness, while minimizing the overall impact to the microgravity environment. The biomedical findings as well as the hardware development results realized from the EDOMP have been important to the continuing success of extended Space Shuttle flights and have formed the basis for medical studies of crew members living for three to five months aboard the Russian space station, Mir. EDOMP data and hardware are also being used in preparation for the construction and habitation of International Space Station. All data sets were grouped to be non-attributable to individuals, and submitted to NASA s Life Sciences Data Archive.

  1. Orbit of the Ophiuchus Stream

    NASA Astrophysics Data System (ADS)

    Sesar, Branimir; Bernard, Edouard J.; Bovy, Jo; Cohen, Judith G.; Caldwell, Nelson; Ness, Melissa; Johnson, Christian I.; Ferguson, Annette M. N.; Martin, Nicolas; Rix, Hans-Walter; Ford Schlafly, Eddie; Pan-Starrs1 Collaboration

    2015-01-01

    Ophiuchus Stream is the most recently discovered stellar stream in the Milky Way (Bernard et al. 2014). Due to its location (?5 kpc from the Galactic center) and its puzzling morphology (a thin and short stream, and yet with no visible progenitor), this stream may represent an important piece in our efforts to understand the Galactic potential and the dynamical evolution of accreted structures. In this talk, I will present a followup study of the stream during which we obtained high-quality spectroscopic data on 14 stream member stars using Keck and MMT telescopes. I will show how these newly acquired spectroscopic and existing photometric data enabled us to constrain i) the distance and line-of-sight extent of the stream, ii) the full 3D kinematics of the stream, iii) the chemical properties of the stream and the nature of its progenitor, and iv) the orbit of the stream. I will finish by discussing future prospects in this field in light of the upcoming public release of Pan-STARRS1, Palomar Transient Factory, and GAIA data.

  2. Gravity and Orbits: Universal Gravitational

    NSDL National Science Digital Library

    National Science Teachers Association (NSTA)

    2006-11-01

    This Science Object is the first of three Science Objects in the Gravity and Orbits SciPack. It provides an understanding of gravitational forces associated with all objects that have mass. Every object exerts a gravitational force on every other object. The force is hard to detect unless at least one of the objects has a lot of mass. Any two objects will exert an equal gravitational force (in opposite directions) on one another. Gravity is the force behind the falling rain and flowing rivers, and is responsible for pulling the matter that makes up planets and stars toward their centers to form spheres. Learning Outcomes:? Identify gravity as an attractive force associated with all objects, including less intuitive examples (such as soda cans and pencils).? Recognize some examples of phenomena that are the result of Earth's gravity and objects and structures in the universe in general.? Reject the idea that Earth's gravity is an effect of air pushing down toward the surface.? Recognize that gravitational force does not require air (or any other substance) as a medium to act.? Describe gravitational force as a mutual attraction, rather than as one object pulling on another.

  3. Gravity and Orbits: Gravitational Force

    NSDL National Science Digital Library

    National Science Teachers Association (NSTA)

    2006-11-01

    This Science Object is the second of three Science Objects in the Gravity and Orbits SciPack. It investigates the variables that influence gravitational forces acting on objects. Mass is a measure of the amount of matter that makes up an object (regardless of where that object is located) and weight is a measure of the gravitational force acting on an object. The strength of the gravitational force between masses is proportional to the product of the masses and inversely proportional to the square of the distance between them. Gravity will cause all objects at the same distance from Earth's surface to fall toward Earth with the same acceleration regardless of their mass. Learning Outcomes:? Identify variables that affect the strength of the gravitational force acting between any two objects.? Provide a quantitative description of the relationship between the mass of two object and the gravitational force between them.? Provide a qualitative description of the relationship between the mass of two objects and the gravitational force between them.? Provide a quantitative description of the relationship between distance and gravitational force. ? Provide a qualitative description of the inverse square relationship.? Recognize the effect of air resistance on object falling near Earth's surface, and thus be able to explain why two objects with different masses, at the same distance from Earth's surface, will have equal accelerations if air resistance is ignored.

  4. Orbital Debris Environment Assessment and Mitigation for Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2007-01-01

    This viewgraph presentation reviews the debris that is in orbit, and reduction of the orbital debris. Specifically, attention is paid to the reduction of orbital debris from launch vehicle stages after the launch.

  5. Satellite orbits design using frequency analysis

    NASA Astrophysics Data System (ADS)

    Noullez, A.; Tsiganis, K.; Tzirti, S.

    2015-07-01

    We present here a new method for the efficient computation of periodic orbits, which are of particular interest for low-altitude satellite orbits design in high degree/order, non-axisymmetric gravity models. Our method consists of an iterative filtering scheme, that is itself based on 'Prony's method' of frequency analysis, and is independent of the complexity of the gravity model. Applying this method to the case of a low-altitude lunar orbiter, we show that it converges rapidly, in all models and for all values of altitude and initial inclination studied. Thus, as demonstrated below, one could use it to correct the initial conditions of a desired mission orbit - usually defined within the framework of a simplified model (e.g. the 'J2 problem') - ensuring minimal orbital eccentricity variations and, for very low altitudes, collision avoidance. At the same time, an accurate quasi-periodic decomposition of the orbit is computed, giving a measure of the periodic fluctuations of the orbital parameters.

  6. Orbital refill of propulsion vehicle tankage

    NASA Technical Reports Server (NTRS)

    Merino, F.; Risberg, J. A.; Hill, M.

    1980-01-01

    Techniques for orbital refueling of space based vehicles were developed and experimental programs to verify these techniques were identified. Orbital refueling operations were developed for two cryogenic orbital transfer vehicles (OTV's) and an Earth storable low thrust liquid propellant vehicle. Refueling operations were performed assuming an orbiter tanker for near term missions and an orbital depot. Analyses were conducted using liquid hydrogen and N2O4. The influence of a pressurization system and acquisition device on operations was also considered. Analyses showed that vehicle refill operations will be more difficult with a cryogen than with an earth storable. The major elements of a successful refill with cryogens include tank prechill and fill. Propellant quantities expended for tank prechill appear to to insignificant. Techniques were identified to avoid loss of liquid or excessive tank pressures during refill. It was determined that refill operations will be similar whether or not an orbiter tanker or orbital depot is available. Modeling analyses were performed for prechill and fill tests to be conducted assuming the Spacelab as a test bed, and a 1/10 scale model OTV (with LN2 as a test fluid) as an experimental package.

  7. The Statistical Mechanics of Planet Orbits

    NASA Astrophysics Data System (ADS)

    Tremaine, Scott

    2015-07-01

    The final “giant-impact” phase of terrestrial planet formation is believed to begin with a large number of planetary “embryos” on nearly circular, coplanar orbits. Mutual gravitational interactions gradually excite their eccentricities until their orbits cross and they collide and merge; through this process the number of surviving bodies declines until the system contains a small number of planets on well-separated, stable orbits. In this paper we explore a simple statistical model for the orbit distribution of planets formed by this process, based on the sheared-sheet approximation and the ansatz that the planets explore uniformly all of the stable region of phase space. The model provides analytic predictions for the distribution of eccentricities and semimajor axis differences, correlations between orbital elements of nearby planets, and the complete N-planet distribution function, in terms of a single parameter, the “dynamical temperature,” that is determined by the planetary masses. The predicted properties are generally consistent with N-body simulations of the giant-impact phase and with the distribution of semimajor axis differences in the Kepler catalog of extrasolar planets. A similar model may apply to the orbits of giant planets if these orbits are determined mainly by dynamical evolution after the planets have formed and the gas disk has disappeared.

  8. Moonport: Transportation node in lunar orbit

    NASA Technical Reports Server (NTRS)

    1987-01-01

    An orbital transporation system between the Earth and Moon was designed. The design work focused on the requirements and configuration of an orbiting lunar base. The design utilized current Space Station technologies, but also focused on the specific requirements involved with a permanently manned, orbiting lunar station. A model of the recommended configuration was constructed. In order to analyze Moonport activity and requirements, a traffic model was designed, defining traffic between the lunar port, or Moonport and low Earth orbit. Also, a lunar base model was used to estimate requirements of the surface base on Moonport traffic and operations. A study was conducted to compare Moonport traffic and operations based in low lunar orbit and the L (sub 2) equilibrium point, behind the Moon. The study compared delta-V requirements to each location and possible payload deliveries to low Earth orbit from each location. Products of the Moonport location study included number of flights annually to Moonport, net payload delivery to low Earth orbit, and Moonport storage requirement.

  9. Titan Orbiter with Aerorover Mission (TOAM)

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.; Cooper, J. F.; Mahaffy, P.; Esper, J.; Fairbrother, D.; Farley, R.; Pitman, J.; Kojiro, D. R.; Acuna, M.; Allen, M.; Bjoraker, G.; Brasunas, J.; Farrell, W.; Burchell, M. J.; Burger, M.; Chin, G.; Coates, A. J.; Farrell, W.; Flasar, M.; Gerlach, B.; Gorevan, S.; Hartle, R. E.; Im, Eastwood; Jennings, D.; Johnson, R. E.

    2007-01-01

    We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. One could also use aerobraking to put spacecraft into orbit around Saturn first for an Enceladus phase of the mission and then later use aerocapture to put spacecraft into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG approx. 1000 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan's atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

  10. The Anomalous Orbital Motion Of Mab Explained

    NASA Astrophysics Data System (ADS)

    Kumar, Kartik; de Pater, I.; Showalter, M. R.

    2012-10-01

    Showalter and Lissauer (2003) reported the discovery of two previously unknown inner satellites of Uranus (Mab and Cupid), using data from the Hubble Space Telescope (HST). Subsequently, they announced the discovery of an outer ring system composed of the ?-ring and the ?-ring (Showalter and Lissauer, 2006). They showed that the orbit of Mab, embedded in the ?-ring, is not well understood, after comparing its orbital position derived from Voyager flyby data (1986) to HST data (2003-2006). The observed positions were compared with a Keplerian orbital model that included the gravitational flattening of Uranus. Although this model works well for nine other Uranian moons, for Mab the fitting errors are six times larger. Mab is relatively bright in the data and well isolated from the other moons, suggesting that the measurement errors should not be large. Hence, the magnitude of the orbit fit residual seems to indicate that we are currently overlooking an essential part of the dynamics that determines the orbit of Mab. It is clear from these discoveries that Mab and the ?-ring are intriguing, constituting "a densely packed, rapidly varying, and possibly unstable dynamical system." We investigated the nature of Mab's anomalous orbital motion, which has thus far remained unexplained. The dynamical effects we simulated result from the interaction of Mab with a hypothetical ring of undetected moonlets in its neighborhood. We explored the effects of varying the characteristics of such a ring (mass and orbital-element distribution) on Mab's orbital motion. From these results we are able to highlight a number of interesting dynamical regimes. In particular, our simulations reveal the important role that perturbers occupying horseshoe orbits might play in determining the perturbations experienced by Mab. Further studies will be conducted to investigate the long-term stability of a possible perturber ring.

  11. Radar observations in low earth orbit

    NASA Astrophysics Data System (ADS)

    Mehrholz, Dieter

    1997-05-01

    This paper presents an overview on radar techniques for the observation of space debris in low Earth orbits which were developed at FGAN in the frame of DARA and ESA/ESOC study contracts for the employment of the Tracking and Imaging Radar (TIRA) system in the past five years. For space debris observations TIRA is mainly operated in two different modes: In a tracking mode and in a beam-park mode of operation. Methods and algorithms were developed to analyse raw radar data, to compute radar images, and to estimate physical characteristics of space objects like size, shape, attitude, orbit, orbital lifetime, ballistic coefficient, mass, and material composition.

  12. Self-shadowing of orbiting trusses

    NASA Technical Reports Server (NTRS)

    Mahaney, J.; Thornton, E. A.

    1983-01-01

    The approach used to assess shadowing reductions on the heating of orbiting trusses involves determining the heating rates with slender member shadowing effects included and then obtaining the thermal response of the shadowed member. Steps taken to identify shadowers, find locations where shadowing occurs and calculate shadow intensity are listed. The finite element thermal structural analysis of cable stiffened space structure is delineated and the exact solution of the caternary problem is given. Typical cable surface heating rates are plotted. The structural analysis includes large deformation (nonlinear), thermal effect, and the pretension effect. Displacements and stresses are computed at different orbital positions for an orbit.

  13. Evolution of asteroidal orbits with high inclinations

    NASA Astrophysics Data System (ADS)

    Solovaya, Nina A.; Pittich, Eduard M.

    1993-10-01

    The 20,000 years orbital evolution of massless fictitious asteroid located at a border of the Hill's gravitational sphere has been investigated. The eleven orbits with the eccentricities from 0.0 to 0.4 in five groups of inclinations from 40 deg to 80 deg were numerically integrated with planetary perturbations of six major planets, using the numerical integration n-body program with the Everhart's integrator RA 15. For each group time evolution of orbital elements of the asteroids is presented.

  14. The orbital mechanics of flight mechanics

    NASA Technical Reports Server (NTRS)

    Dunning, R. S.

    1973-01-01

    A reference handbook on modern dynamic orbit theory is presented. Starting from the most basic inverse-square law, the law of gravity for a sphere is developed, and the motion of point masses under the influence of a sphere is considered. The reentry theory and the orbital theory are discussed along with the relative motion between two bodies in orbit about the same planet. Relative-motion equations, rectangular coordinates, and the mechanics of simple rigid bodies under the influence of a gravity gradient field are also discussed.

  15. Histological patterns in orbital malignant tumors.

    PubMed

    Ibric-Cioranu, Viorel; Nicolae, Vasile; Iorgulescu, Daniel; F?ge?an, Iulian Mihai; Petrescu Seceleanu, Vlad; Cernu?c?-Mi?ariu, Mihaela; Nicolae, Silviu; Ibric-Cioranu, Sorin

    2014-01-01

    There is a wide variety of tumors affecting the orbit. The most encountered histological type of malignant orbital tumor is the basal cell carcinoma followed by the malignant melanoma and the squamous cell carcinoma. The authors conducted a retrospective review of the malignant orbit tumors from the Department of Oral and Maxillofacial Surgery, University Emergency Hospital of Sibiu, Romania. The main surgical methods implied were tumor resection, exenteration and extended exenteration. The reconstruction was performed with the help of local flaps using different techniques: advancement, translation or rotation. The use of local flaps allowed for a good esthetic outcome and a decrease in the healing time. PMID:25178348

  16. Machine vision for real time orbital operations

    NASA Technical Reports Server (NTRS)

    Vinz, Frank L.

    1988-01-01

    Machine vision for automation and robotic operation of Space Station era systems has the potential for increasing the efficiency of orbital servicing, repair, assembly and docking tasks. A machine vision research project is described in which a TV camera is used for inputing visual data to a computer so that image processing may be achieved for real time control of these orbital operations. A technique has resulted from this research which reduces computer memory requirements and greatly increases typical computational speed such that it has the potential for development into a real time orbital machine vision system. This technique is called AI BOSS (Analysis of Images by Box Scan and Syntax).

  17. Symmetry orbits of supergravity black holes

    NASA Astrophysics Data System (ADS)

    Stelle, K. S.

    2015-01-01

    Black-hole solutions of supergravity theories form families that realize the deep nonlinear "duality" symmetries of these theories. They form orbits under the action of these symmetry groups, with extremal (i.e., BPS) solutions at the limits of such orbits. An important technique for analyzing such solution families uses timelike dimensional reduction and exchanges the stationary black-hole problem for a nonlinear sigma-model problem. We characterize families of extremal or BPS solutions by nilpotent orbits under the duality symmetries, based on a trigraded or pentagraded decomposition of the corresponding duality-group algebra.

  18. Orbital motion under continuous tangential thrust

    NASA Technical Reports Server (NTRS)

    Boltz, Frederick W.

    1992-01-01

    The effect of continuous tangential thrust on the orbital motion and mass loss of a vehicle initially in a circular orbit is investigated analytically. It is shown that, for a thrust-to-weight ratio of greater than 0.16175, escape speed will eventually be reached along an unwinding spiral trajectory. For lower thrust-to-weight ratios, escape speed is never attained, and the flight path oscillates around a logarithmic spiral trajectory. Formulas are obtained for the approximate orbital motion and time of flight along each type of trajectory and for mass loss due to expenditure of rocket propellant.

  19. Re-determination of Phoebe's orbit

    NASA Astrophysics Data System (ADS)

    Shen, K. X.; Harper, D.; Qiao, R. C.; Dourneau, G.; Liu, J. R.

    2005-07-01

    In order to improve the orbit of Phoebe, the ninth satellite of the Saturnian system, 101 new observations were made by our research team in 2003, using a CCD detector of large size (2048×2048 pixels) mounted on the 1.56 m astrometric reflector at the Sheshan Station of Shanghai Astronomical Observatory. We fitted a numerical integration of its orbit to all of the collected Earth-based astrometric observations from 1904 to 2003, including the newest precise data sets from Qiao & Tang and from Peng et al. A new set of initial conditions of Phoebe has been obtained, leading to an improved orbit of this satellite.

  20. I: PRECISE ORBIT DETERMINATION AND GRAVITY FIELD MODELLING: Strategies for Precise Orbit Determination of Low Earth Orbiters Using the GPS

    Microsoft Academic Search

    U. Hugentobler; G. Beutler

    2003-01-01

    Considerable experience accumulated during the past decade in strategies for processing GPS data from ground-based geodetic\\u000a receivers. First experience on the use of GPS observations from spaceborne receivers for orbit determination of satellites\\u000a on low altitude orbits was gained with the launch of TOPEX\\/POSEIDON ten years ago. The launch of the CHAMP satellite in July\\u000a 2000 stimulated a number of

  1. The Carter Constant for Inclined Orbits About a Massive Kerr Black Hole: I. circular orbits

    E-print Network

    P. G. Komorowski; S. R. Valluri; M. Houde

    2011-01-19

    In an extreme binary black hole system, an orbit will increase its angle of inclination (i) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar orbits; and develop an analysis that is independent of and complements radiation reaction models. For a Schwarzschild black hole, the polar orbits represent the abutment between the prograde and retrograde orbits at which Q is at its maximum value for given values of latus rectum (l) and eccentricity (e). The introduction of spin (S = |J|/M2) to the massive black hole causes this boundary, or abutment, to be moved towards greater orbital inclination; thus it no longer cleanly separates prograde and retrograde orbits. To characterise the abutment of a Kerr black hole (KBH), we first investigated the last stable orbit (LSO) of a test-particle about a KBH, and then extended this work to general orbits. To develop a better understanding of the evolution of Q we developed analytical formulae for Q in terms of l, e, and S to describe elliptical orbits at the abutment, polar orbits, and last stable orbits (LSO). By knowing the analytical form of dQ/dl at the abutment, we were able to test a 2PN flux equation for Q. We also used these formulae to numerically calculate the di/dl of hypothetical circular orbits that evolve along the abutment. From these values we have determined that di/dl = -(122.7S - 36S^3)l^-11/2 -(63/2 S + 35/4 S^3) l^-9/2 -15/2 S l^-7/2 -9/2 S l^-5/2. Thus the abutment becomes an important analytical and numerical laboratory for studying the evolution of Q and i in Kerr spacetime and for testing current and future radiation back-reaction models for near-polar retrograde orbits.

  2. Back to the Future: The Return to Heliocentrism

    E-print Network

    Walter, Frederick M.

    as a predictor to Ptolemy's model De Revolutionibus Orbium Coelestium (1543) #12;Tycho Brahe (1546-1601 a supernova #12;Tycho's Motivation Failure to detect parallax required either ·Earth was stationary, or ·Stars were very far away How far? ·Tycho could measure about 1 arcmin ·Using parallax, the distance in AU = 1

  3. Thermal Stability Analysis for a Heliocentric Gravitational Radiation Detection Mission

    NASA Technical Reports Server (NTRS)

    Folkner, W.; McElroy, P.; Miyake, R.; Bender, P.; Stebbins, R.; Supper, W.

    1994-01-01

    The Laser Interferometer Space Antenna (LISA) mission is designed for detailed studies of low-frequency gravitational radiation. The mission is currently a candidate for ESA's post-Horizon 2000 program. Thermal noise affects the measurement in at least two ways. Thermal variation of the length of the optical cavity to which the lasers are stabilized introduces phase variations in the interferometer signal, which have to be corrected for by using data from the two arms separately.

  4. Optimal control laws for heliocentric transfers with a magnetic sail

    NASA Astrophysics Data System (ADS)

    Quarta, Alessandro A.; Mengali, Giovanni; Aliasi, Generoso

    2013-08-01

    A magnetic sail is an advanced propellantless propulsion system that uses the interaction between the solar wind and an artificial magnetic field generated by the spacecraft, to produce a propulsive thrust in interplanetary space. The aim of this paper is to collect the available experimental data, and the simulation results, to develop a simplified mathematical model that describes the propulsive acceleration of a magnetic sail, in an analytical form, for mission analysis purposes. Such a mathematical model is then used for estimating the performance of a magnetic sail-based spacecraft in a two-dimensional, minimum time, deep space mission scenario. In particular, optimal and locally optimal steering laws are derived using an indirect approach. The obtained results are then applied to a mission analysis involving both an optimal Earth-Venus (circle-to-circle) interplanetary transfer, and a locally optimal Solar System escape trajectory. For example, assuming a characteristic acceleration of 1 mm/s2, an optimal Earth-Venus transfer may be completed within about 380 days.

  5. Dust emission of Comet Halley at large heliocentric distances

    NASA Technical Reports Server (NTRS)

    Gruen, E.; Schwehm, G.; Massonne, L.; Fertig, J.; Graser, U.

    1985-01-01

    Comet Halley is currently approaching the inner solar system. Four spacecrafts (NASA's spacecraft, two Russian Vega probes and the Japanese MS-T5 spacecraft) have already been launched to encounter the comet in March 1986. Two additional Halley probes (the European Giotto spacecraft and another Japanese Planet-A probe) will be launched in mid-85 to join the armada. Observations of dust emissions from Halley's Comet are discussed. The evaporation of cometary ices causes the emission of particulates from the nucleus. These observations will be used to determine the fly-by strategy of the Giotto spacecraft by taking into account the distribution of dust in the vicinity of the nucleus and the associated hazard for the space mission.

  6. The forward-reverse shock pair at large heliocentric distances

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1984-01-01

    An unsteady one-dimensional numerical magnetohydrodynamic (MHD) model is developed in order to study the essential physical processes involved in the development of the forward-reverse shock pair in the heliosphere. In the model, MHD shocks are treated as boundary surfaces which divide the domain of interest in the r-t plane into several flow regions. The positions of the shock boundary surfaces between two neighboring flow regions are determined by shock speed. On the basis of integrations of the model, it is found that the strong MHD disturbances generated in a corotating interaction region (CIR) propagate at a fast speed relative to the moving material, and that the wave propagation speed is greater in CIR than in its surroundings. This causes disturbances in CIR to pile up and form a shock pair. The newly formed shock pair will in turn propagate outward from the leading edge to interact with ambient rarefaction regions. This interaction accounts for the double sawtooth configuration observed in velocity profiles of shock pairs. It is also demonstrated that the merging of two shocks produces a stronger shock and constant surface on its backside. Computer generated velocity profiles based on the model are presented.

  7. Heliocentric interplanetary low thrust trajectory optimization program, supplement 1

    NASA Technical Reports Server (NTRS)

    Mann, F. I.; Horsewood, J. L.

    1974-01-01

    The modifications and improvements made to the HILTOP electric propulsion trajectory optimization computer program up through the end of 1974 is described. New program features include the simulation of power degradation, housekeeping power, launch asymptote declination optimization, and powered and unpowered ballistic multiple swingby missions with an optional deep space burn. The report contains the new analysis describing these features, a complete description of program input quantities, and sample cases of computer output illustrating the new program capabilities.

  8. Closed orbit related problems: Correction, feedback, and analysis

    SciTech Connect

    Bozoki, E.S.

    1995-02-01

    Orbit correction - moving the orbit to a desired orbit, orbit stability - keeping the orbit on the desired orbit using feedback to filter out unwanted noise, and orbit analysis - to learn more about the model of the machine, are strongly interrelated. They are the three facets of the same problem. The better one knows the model of the machine, the better the predictions that can be made on the behavior of the machine (inverse modeling) and the more accurately one can control the machine. On the other hand, one of the tools to learn more about the machine (modeling) is to study and analyze the orbit response to {open_quotes}kicks.{close_quotes}

  9. Spacetime and orbits of bumpy black holes

    E-print Network

    Vigeland, Sarah Jane

    Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine ...

  10. Orbiter active thermal control system description

    NASA Technical Reports Server (NTRS)

    Laubach, G. E.

    1975-01-01

    A brief description of the Orbiter Active Thermal Control System (ATCS) including (1) major functional requirements of heat load, temperature control and heat sink utilization, (2) the overall system arrangement, and (3) detailed description of the elements of the ATCS.

  11. Secular Orbital Evolution of Compact Planet Systems

    E-print Network

    Zhang, Ke; Matsumura, Soko

    2013-01-01

    Recent observations have shown that at least some close-in exoplanets maintain eccentric orbits despite tidal circularization timescales that are typically shorter than stellar ages. We explore gravitational interactions with a distant planetary companion as a possible cause of these non-zero eccentricities. For simplicity, we focus on the evolution of a planar two-planet system subject to slow eccentricity damping and provide an intuitive interpretation of the resulting long-term orbital evolution. We show that dissipation shifts the two normal eigenmode frequencies and eccentricity ratios of the standard secular theory slightly, and that each mode decays at its own rate. Tidal damping of the eccentricities drives orbits to transition between periods of pericenter circulation and libration, and the planetary system settles into a locked state where the pericenters are nearly aligned or antialigned. Once in the locked state, the eccentricities of the two orbits decrease very slowly due to tides rather than at...

  12. Orbit determination for next generation space clocks

    NASA Astrophysics Data System (ADS)

    Duchayne, L.; Mercier, F.; Wolf, P.

    2009-09-01

    We study the requirements on orbit determination compatible with operation of next generation space clocks at their expected uncertainty. Using the ACES (Atomic Clock Ensemble in Space) mission as an example, we develop a relativistic model for time and frequency transfer to investigate the effects of orbit determination errors. For the orbit error models considered we show that the required uncertainty goal can be reached with relatively modest constraints on the orbit determination of the space clock, which are significantly less stringent than expected from “naive” estimates. Our results are generic to all space clocks and represent a significant step towards the generalized use of next generation space clocks in fundamental physics, geodesy, and time/frequency metrology.

  13. Asteroid orbital error analysis: Theory and application

    NASA Technical Reports Server (NTRS)

    Muinonen, K.; Bowell, Edward

    1992-01-01

    We present a rigorous Bayesian theory for asteroid orbital error estimation in which the probability density of the orbital elements is derived from the noise statistics of the observations. For Gaussian noise in a linearized approximation the probability density is also Gaussian, and the errors of the orbital elements at a given epoch are fully described by the covariance matrix. The law of error propagation can then be applied to calculate past and future positional uncertainty ellipsoids (Cappellari et al. 1976, Yeomans et al. 1987, Whipple et al. 1991). To our knowledge, this is the first time a Bayesian approach has been formulated for orbital element estimation. In contrast to the classical Fisherian school of statistics, the Bayesian school allows a priori information to be formally present in the final estimation. However, Bayesian estimation does give the same results as Fisherian estimation when no priori information is assumed (Lehtinen 1988, and reference therein).

  14. Dacryocystography in a cat with orbital pneumatosis.

    PubMed

    Meomartino, Leonardo; Pasolini, Maria P; Lamagna, Francesco; Santangelo, Bruna; Mennonna, Giuseppina; Della Valle, Giovanni; Lamagna, Barbara

    2015-03-01

    A 2-year-old neutered male European short-haired cat was presented for a persistent discharge from the scar of previous left eye enucleation, performed 6 months prior by the referring veterinarian. A surgical exploration of the orbit was performed and retained nictitating membrane glandular and conjunctival tissues were removed. Eleven days later, the cat developed an orbital pneumatosis caused by retrograde movement of air through a patent nasolacrimal system and diagnosed by survey radiographic examination of the skull. Nasolacrimal system patency was assessed by dacryocystography performed by injection of iodinated contrast medium under pressure into the orbital cavity. Computed tomography dacryocystography confirmed the radiographic findings. The condition resolved following dacryocystography, possibly as an inflammatory response to the contrast medium. To our knowledge, this is the first case of orbital pneumatosis reported in a cat. PMID:24118801

  15. Mars Exploration Rover cruise orbit determination

    NASA Technical Reports Server (NTRS)

    Portock, Brian; Baird, Darren; Graat, Eric; McElrath, Tim; Watkins, Michael; Wawrzyniak, Geoff

    2004-01-01

    This paper will describe the results of the orbit determination process for each mission, MER-A and MER-B, during their cruise phase to Mars ending with there final approach to Mars atmospheric entry.

  16. An approach to autonomous, onboard orbit determination

    NASA Technical Reports Server (NTRS)

    Mease, K. D.; Ryne, M. S.; Wood, L. J.

    1984-01-01

    An orbit determination subsystem that will operate as an integral part of an autonomous, onboard navigation system is presented and analyzed. The navigation system is required to interface solely with the downlink telemetry stream and uplink command stream of an existing class of geostationary satellites. In particular, the orbit will be determined from a set of onboard sensors, which previously were used only for attitude determination. The design of the orbit determination subsystem is described in detail. The rationale behind the choice of each component of the design is given. Finally, the performance of the orbit determination subsystem, under a variety of assumptions, is determined by a combination of numerical simulation and analytical methods.

  17. Orbital precession in Hercules X-1

    NASA Technical Reports Server (NTRS)

    Deeter, J. E.; Boynton, P. E.

    1976-01-01

    It is noted that the 35-day X-ray high-low cycle of Her X-1 could be explained in terms of periodic obscuration of the source by a tilted and precessing 'slaved' accretion disk, which would require precession of the mass-shedding star and, consequently, a precessing binary orbit. Four months of Uhuru data obtained in 1972 are analyzed to determine whether the orbital precession can be detected as a Doppler modulation in the arrival times of the 1.24-sec X-ray pulsations. The precession geometry is examined, the test for precession is outlined, and a marginally significant indication of orbital precession in the Hz Her/Her X-1 system is obtained. Possible biases in the analysis are evaluated, and the spin-axis misalignment of HZ Her is estimated from the measured tilt of the orbit.

  18. Characterizing orbit uncertainty due to atmospheric uncertainty 

    E-print Network

    Wilkins, Matthew Paul

    2000-01-01

    is performed. Currently, USSPACECOM uses a batch least squares orbit prediction method which assumes a perfect dynamic model, and then uses empirical methods to artificially inflate the covariance. However, these techniques often have no physical basis...

  19. Orbital debris : drafting, negotiating, implementing a convention

    E-print Network

    Sénéchal, Thierry

    2007-01-01

    It is time to recognize that while space may be infinite, Earth orbital space is a finite natural resource that must be managed properly. The problem we face with space pollution is complex and serious. The space treaties ...

  20. Calculation of eclipses for elliptical orbits

    NASA Astrophysics Data System (ADS)

    Kuga, Helio K.; Guedes, Ulisses T. V.

    1987-10-01

    The theoretical development of the eclipse phenomenon which occurs in orbits of artificial satellites is presented. The procedure was implemented in the computer, in standard FORTRAN language. Tests, user's manual, and an appendix containing the program listing are included.

  1. ORBITS IN THE LEECH LATTICE DANIEL ALLCOCK

    E-print Network

    Allcock, Daniel

    ORBITS IN THE LEECH LATTICE DANIEL ALLCOCK Abstract. We provide an algorithm for determining whether two vectors in the Leech lattice the performance of the algorithm. 1. Introduction The Leech lattice is a lattice

  2. Spinning compact binary dynamics and chameleon orbits

    E-print Network

    László Árpád Gergely; Zoltán Keresztes

    2014-12-20

    We analyse the conservative evolution of spinning compact binaries to second post-Newtonian (2PN) order accuracy, with leading order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. As a main result we derive a closed system of first order differential equations in a compact form, for a set of dimensionless variables encompassing both orbital elements and spin angles. These evolutions are constrained by conservation laws holding at 2PN order. As required by the generic theory of constrained dynamical systems we perform a consistency check and prove that the constraints are preserved by the evolution. We apply the formalism to show the existence of chameleon orbits, whose local, orbital parameters evolve from elliptic (in the Newtonian sense) near pericenter, towards hyperbolic at large distances. This behavior is consistent with the picture that General Relativity predicts stronger gravity at short distances than Newtonian theory does.

  3. Mars orbiter conceptual systems design study

    NASA Technical Reports Server (NTRS)

    Dixon, W.; Vogl, J.

    1982-01-01

    Spacecraft system and subsystem designs at the conceptual level to perform either of two Mars Orbiter missions, a Climatology Mission and an Aeronomy Mission were developed. The objectives of these missions are to obtain and return data.

  4. Orbiting quarantine facility. The Antaeus report

    NASA Technical Reports Server (NTRS)

    Devincenzi, D. L. (editor); Bagby, J. R. (editor)

    1981-01-01

    A mission plan for the Orbiting Quarantine Facility (OQF) is presented. Coverage includes system overview, quarantine and protocol, the laboratory, support systems, cost analysis and possible additional uses of the OQF.

  5. STS mission duration enhancement study: (orbiter habitability)

    NASA Technical Reports Server (NTRS)

    Carlson, A. D.

    1979-01-01

    Habitability improvements for early flights that could be implemented with minimum impact were investigated. These included: (1) launching the water dispenser in the on-orbit position instead of in a locker; (2) the sleep pallet concept; and (3) suction cup foot restraints. Past studies that used volumetric terms and requirements for crew size versus mission duration were reviewed and common definitions of key habitability terms were established. An accurately dimensioned drawing of the orbiter mid-deck, locating all of the known major elements was developed. Finally, it was established that orbiter duration and crew size can be increased with minimum modification and impact to the crew module. Preliminary concepts of the aft med-deck, external versions of expanded tunnel adapters (ETA), and interior concepts of ETA-3 were developed and comparison charts showing the various factors of volume, weight, duration, size, impact to orbiter, and number of sleep stations were generated.

  6. Spin-orbit interactions of light

    E-print Network

    Bliokh, K Y; Nori, F; Zayats, A V

    2015-01-01

    Light carries spin and orbital angular momentum. These dynamical properties are determined by the polarization and spatial degrees of freedom of light. Modern nano-optics, photonics, and plasmonics, tend to explore subwavelength scales and additional degrees of freedom of structured, i.e., spatially-inhomogeneous, optical fields. In such fields, spin and orbital properties become strongly coupled with each other. We overview the fundamental origins and important applications of the main spin-orbit interaction phenomena in optics. These include: spin-Hall effects in inhomogeneous media and at optical interfaces, spin-dependent effects in nonparaxial (focused or scattered) fields, spin-controlled shaping of light using anisotropic structured interfaces (metasurfaces), as well as robust spin-directional coupling via evanescent near fields. We show that spin-orbit interactions are inherent in all basic optical processes, and they play a crucial role at subwavelength scales and structures in modern optics.

  7. Apollo 11 (launch, on moon, in orbit)

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The Apollo 11 Command and Service Modules are shown in a photo taken from the Lunar Module while in orbit around the Moon. Photograph published in Winds of Change, 75th Anniversary NASA publication (page 98), by James Schultz.

  8. Orbital Transfer Vehicle (space taxi) with aerobraking at Earth and Mars

    NASA Technical Reports Server (NTRS)

    1987-01-01

    This report shall cover all major aspects of the design of an Aeroassisted Manned Transfer Vehicle (or TAXI) for use as part of advanced manned Mars missions based on a cycling ship concept. Along with the heliocentric orbiting Cycling Spacecraft, such a TAXI would be a primary component of a long-term transportation system for Mars exploration. The Aeroassisted Manned Transfer Vehicle (AMTV) design developed shall operate along transfer trajectories between Earth and a Cycling Spacecraft (designed by the University of Michigan) and Mars. All operations of the AMTV shall be done primarily within the sphere of influence of the two planets. Maximum delta-V's for the vehicle have been established near 9 km/sec, with transfer durations of about 3 days. Acceleration deltaV's will be accomplished using 3 SSME-based hydrogen-oxygen chemical rockets (l(sub sp) = 485 sec & Thrust greater than = 300,00 Ib(sub f)/engine) with a thrust vector directly opposite the aerobraking deceleration vector. The aerobraking deceleration portion of an AMTV mission would be accomplished in this design by a moderate L/D aeroshield of an ellipsoidally-blunt, raked-off, elliptic cone (EBROEC) shape. The reusable thermal protection material comprising the shield will consist of a flexible, multi-layer, ceramic fabric stretched over a lightweight, rigid, shape - defining truss structure. Behind this truss, other components, including the engine supports, would be attached and protected from heating during aerobraking passes. Among these other components would be 2 LOX tanks and 4 LH2 tanks (and their support frames) holding over 670,000 lbm of propellant necessary to impart the required delta-V to the 98,000 lbm burnout mass vehicle. A 20,000 lbm crew module with docking port (oriented parallel to the accel./decel. axis) will provide accommodations for 9 crew members (11 under extreme conditions) for durations up to seven days, thus allowing extra time for emergency situations. This AMTV will be equipped with complete guidance, navigation, control and communications systems modules attached near the crew module. Control of vehicle attitude will be provided by a set of small reaction control thrusters quite similar to those on the current Space Shuttle. All crew module and vehicle electrical functions will be powered via a set of H2/O2 fuel cells with radio-isotopic generators as backup supplies. Also included in the burnout mass of 98,000 lb is allowance for 10,000 lbm of miscellaneous payload (scientific equipment or other supplies).

  9. Quaternion Solution for the Rock'n'roller: Box Orbits, Loop Orbits and Recession

    E-print Network

    Peter Lynch; Miguel D Bustamante

    2012-07-25

    We consider two types of trajectories found in a wide range of mechanical systems, viz. box orbits and loop orbits. We elucidate the dynamics of these orbits in the simple context of a perturbed harmonic oscillator in two dimensions. We then examine the small-amplitude motion of a rigid body, the rock'n'roller, a sphere with eccentric distribution of mass. The equations of motion are expressed in quaternionic form and a complete analytical solution is obtained. Both types of orbit, boxes and loops, are found, the particular form depending on the initial conditions. We interpret the motion in terms of epi-elliptic orbits. The phenomenon of recession, or reversal of precession, is associated with box orbits. The small-amplitude solutions for the symmetric case, or Routh sphere, are expressed explicitly in terms of epicycles; there is no recession in this case.

  10. New osculating orbits for 110 comets and analysis of original orbits for 200 comets

    NASA Technical Reports Server (NTRS)

    Marsden, B. G.; Sekanina, Z.; Everhart, E.

    1978-01-01

    Osculating orbits are presented for 110 nearly parabolic comets. Combining these with selected orbit determinations from other sources, a total of 200 orbits are considered where the available observations yield a result of very good (first-class) or good (second-class) quality. For each of these, the original and future orbits (referred to the barycenter of the solar system) are calculated. The Oort effect (a tendency for original reciprocal semimajor axis values to range from zero to +100 millionths per AU) is clearly seen among the first-class orbits but not among the second-class orbits. Modifications in original reciprocal semimajor axis values due to the effects of nongravitational forces are considered.

  11. Orbital relaxation effects on Kohn-Sham frontier orbital energies in density functional theory.

    PubMed

    Zhang, DaDi; Zheng, Xiao; Li, Chen; Yang, Weitao

    2015-04-21

    We explore effects of orbital relaxation on Kohn-Sham frontier orbital energies in density functional theory by using a nonempirical scaling correction approach developed in Zheng et al. [J. Chem. Phys. 138, 174105 (2013)]. Relaxation of Kohn-Sham orbitals upon addition/removal of a fractional number of electrons to/from a finite system is determined by a systematic perturbative treatment. The information of orbital relaxation is then used to improve the accuracy of predicted Kohn-Sham frontier orbital energies by Hartree-Fock, local density approximation, and generalized gradient approximation methods. The results clearly highlight the significance of capturing the orbital relaxation effects. Moreover, the proposed scaling correction approach provides a useful way of computing derivative gaps and Fukui quantities of N-electron finite systems (N is an integer), without the need to perform self-consistent-field calculations for (N ± 1)-electron systems. PMID:25903872

  12. Orbital relaxation effects on Kohn-Sham frontier orbital energies in density functional theory

    NASA Astrophysics Data System (ADS)

    Zhang, DaDi; Zheng, Xiao; Li, Chen; Yang, Weitao

    2015-04-01

    We explore effects of orbital relaxation on Kohn-Sham frontier orbital energies in density functional theory by using a nonempirical scaling correction approach developed in Zheng et al. [J. Chem. Phys. 138, 174105 (2013)]. Relaxation of Kohn-Sham orbitals upon addition/removal of a fractional number of electrons to/from a finite system is determined by a systematic perturbative treatment. The information of orbital relaxation is then used to improve the accuracy of predicted Kohn-Sham frontier orbital energies by Hartree-Fock, local density approximation, and generalized gradient approximation methods. The results clearly highlight the significance of capturing the orbital relaxation effects. Moreover, the proposed scaling correction approach provides a useful way of computing derivative gaps and Fukui quantities of N-electron finite systems (N is an integer), without the need to perform self-consistent-field calculations for (N ± 1)-electron systems.

  13. Controversies in orbital reconstruction--II. Timing of post-traumatic orbital reconstruction: a systematic review.

    PubMed

    Dubois, L; Steenen, S A; Gooris, P J J; Mourits, M P; Becking, A G

    2015-04-01

    The timing of orbital reconstruction is a determinative factor with respect to the incidence of potential postoperative orbital complications. In orbital trauma surgery, a general distinction is made between immediate (within hours), early (within 2 weeks), and late surgical intervention. There is a strong consensus on the indications for immediate repair, but clinicians face challenges in identifying patients with minimal defects who may actually benefit from delayed surgical treatment. Moreover, controversies exist regarding the risk of late surgery-related orbital fibrosis, since traumatic ocular motility disorders sometimes recover spontaneously and therefore do not necessarily require surgery. In this study, all currently available evidence on timing as an independent variable in orbital fracture reduction outcomes for paediatric and adult patients was systematically reviewed. Current evidence supports guidelines for immediate repair but is insufficient to support guidelines on the best timing for non-immediate orbital reconstruction. PMID:25543904

  14. Frozen orbits in the J2 + J3 problem. [orbital mechanics

    NASA Technical Reports Server (NTRS)

    Kiedron, Krystyna; Cook, Richard

    1992-01-01

    An analytical derivation of frozen orbit eccentricities and their location over the range of possible orbital inclinations in the J2 + J3 problem is presented. A gravitational field with only J2 and J3 terms is considered, because the equation defining frozen orbits in this field is an algebraic equation of the third order and an analytical formula for roots of this equation exists. An equation for the frozen orbit eccentricity is derived in a convenient form using only two independent parameters: the inclination and a parameter which is the product of the ratio of the radius of the central body to the orbital semimajor axis and the ratio of the J2 and J3 coefficients. The equation is solved, and, on the basis of its roots, frozen orbits in the J2 + J3 problem are classified.

  15. Calibration of the Lunar Reconnaissance Orbiter Camera

    Microsoft Academic Search

    M. Tschimmel; M. S. Robinson; D. C. Humm; B. W. Denevi; S. J. Lawrence; S. Brylow; M. Ravine; T. Ghaemi

    2008-01-01

    The Lunar Reconnaissance Orbiter Camera (LROC) onboard the NASA Lunar Reconnaissance Orbiter (LRO) spacecraft consists of three cameras: the Wide-Angle Camera (WAC) and two identical Narrow Angle Cameras (NAC-L, NAC-R). The WAC is push-frame imager with 5 visible wavelength filters (415 to 680 nm) at a spatial resolution of 100 m\\/pixel and 2 UV filters (315 and 360 nm) with

  16. Bilateral simultaneous ancient schwannomas of the orbit.

    PubMed

    Sales-Sanz, Marco; Sanz-Lopez, Andrea; Romero, Jose Antonio Canto

    2007-01-01

    An unusual case of purely cystic bilateral ancient schwannomas of the orbit is reported. Complete ophthalmologic examination and CT was performed. Diagnosis was established by excisional biopsy of both tumors, including clinicopathologic study. Histologic examination showed a bilateral purely cystic ancient schwannoma. This case underlines the importance of considering neural tumors, including schwannomas, in the differential diagnosis of both cystic and bilateral orbital tumors. As far as we know, no other case has been previously reported. PMID:17237700

  17. Apollo-Lunar Orbital Rendezvous Technique

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Apollo-Lunar Orbital Rendezvous Technique. The film shows artists rendition of the spacecrafts, boosters, and flight of the Apollo lunar missions. The Apollo spacecraft will consist of three modules: the manned Command Module; the Service Module, which contains propulsion systems; and the Lunar Excursion Module (LEM) to carry astronauts to the moon and back to the Command and Service Modules. The spacecraft will be launched via a three-stage Saturn booster. The first stage will provide 7.5 million pounds of thrust from five F-1 engines for liftoff and initial powered flight. The second stage will develop 1 million pounds of thrust from five J-2 engines to boost the spacecraft almost into Earth orbit. Immediately after ignition of the second stage, the Launch Escape System will be jettisoned. A single J-2 engine in the S4B stage will provide 200,000 pounds of thrust to place the spacecraft in an earth parking orbit. It also will be used to propel the spacecraft into a translunar trajectory, then it will separate from the Apollo Modules. Onboard propulsion systems will be used to insert the spacecraft into lunar orbit. Two astronauts will enter the LEM, which will separate from the command and service modules. The LEM will go into elliptical orbit and prepare for landing. The LEM will lift off of the Moon's surface to return to the Command and Service Modules, and most likely be left in lunar orbit. After leaving the Moon's orbit, and shortly before entering Earth's orbit, the Service Module will be ejected. The Command Module will be oriented for reentry into the Earth's atmosphere. A drogue parachute will deploy at approximately 50,000 feet, followed by the main parachute system for touchdown. [Entire movie available on DVD from CASI as Doc ID 20070030988. Contact help@sti.nasa.gov

  18. (abstract) Hermes Global Orbiter: Mission to Mercury

    NASA Technical Reports Server (NTRS)

    Horn, L.; Nelson, R.; Weiss, J.; Smythe, W.; Evans, M.; Gatz, E.; Kuo, S.; Lane, A.; Linick, S.; Lopes-Gautier, R.; Manatt, K.; Martin, W.; Morris, R.; Ocampo, A.; Spradlin, G.; Wallis, B.; Yen, C.; Danielson, G.; Garvin, J.; Guest, J.; Hapke, B.; McClintock, W.; Simmons, K.; Russell, C.; Cruz, M.

    1993-01-01

    The Hermes Global Orbiter is a proposed Discovery-class mission. Hermes will be launched aboard a Delta II rocket in 1999 and will be placed in an elliptical polar orbit about Mercury. Remote sensing measurements of the planet's surface, atmosphere, and magnetosphere will be performed. Key mission goals include mapping the entire surface at 1 km resolution, characterizing the surface composition, texture and topography, searching for water ice at the poles, characterizing the atmosphere, and constraining the interior structure.

  19. Landsat4 orbit determination using TDRSS

    Microsoft Academic Search

    D. H. Oza; D. J. Niklewski; C. E. Doll; G. D. Mistretta; R. C. Hart

    1995-01-01

    This paper presents the results of a study to compare the orbit determination accuracy for a Tracking and Data Relay Satellite (TDRS) System (TDRSS)-user spacecraft, Landsat-4, obtained using a Prototype Filter Smoother (PFS), with the accuracy of an established batch-least-squares system, the Goddard Trajectory Determination System (GTDS). The results of Landsat-4 orbit determination provide useful experience for the Earth Observing

  20. On modular completion of generalized flux orbits

    E-print Network

    Shukla, Pramod

    2015-01-01

    In the context of type IIB orientifold compactification with the presence of (non-)geometric fluxes, we conjecture a modular completed version of the generalized flux-orbits of various NS-NS and RR fluxes. Subsequently, considering an explicit example with frozen complex structure moduli, we illustrate the utility of these new flux orbits in a `suitable' rearrangement of the four dimensional effective scalar potential which could be relevant for understanding its ten-dimensional origin.